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Diffstat (limited to 'src/analyze.c')
| -rw-r--r-- | src/analyze.c | 2004 |
1 files changed, 2004 insertions, 0 deletions
diff --git a/src/analyze.c b/src/analyze.c new file mode 100644 index 0000000..59e3d98 --- /dev/null +++ b/src/analyze.c @@ -0,0 +1,2004 @@ +/* +** 2005-07-08 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** This file contains code associated with the ANALYZE command. +** +** The ANALYZE command gather statistics about the content of tables +** and indices. These statistics are made available to the query planner +** to help it make better decisions about how to perform queries. +** +** The following system tables are or have been supported: +** +** CREATE TABLE sqlite_stat1(tbl, idx, stat); +** CREATE TABLE sqlite_stat2(tbl, idx, sampleno, sample); +** CREATE TABLE sqlite_stat3(tbl, idx, nEq, nLt, nDLt, sample); +** CREATE TABLE sqlite_stat4(tbl, idx, nEq, nLt, nDLt, sample); +** +** Additional tables might be added in future releases of SQLite. +** The sqlite_stat2 table is not created or used unless the SQLite version +** is between 3.6.18 and 3.7.8, inclusive, and unless SQLite is compiled +** with SQLITE_ENABLE_STAT2. The sqlite_stat2 table is deprecated. +** The sqlite_stat2 table is superseded by sqlite_stat3, which is only +** created and used by SQLite versions 3.7.9 through 3.29.0 when +** SQLITE_ENABLE_STAT3 defined. The functionality of sqlite_stat3 +** is a superset of sqlite_stat2 and is also now deprecated. The +** sqlite_stat4 is an enhanced version of sqlite_stat3 and is only +** available when compiled with SQLITE_ENABLE_STAT4 and in SQLite +** versions 3.8.1 and later. STAT4 is the only variant that is still +** supported. +** +** For most applications, sqlite_stat1 provides all the statistics required +** for the query planner to make good choices. +** +** Format of sqlite_stat1: +** +** There is normally one row per index, with the index identified by the +** name in the idx column. The tbl column is the name of the table to +** which the index belongs. In each such row, the stat column will be +** a string consisting of a list of integers. The first integer in this +** list is the number of rows in the index. (This is the same as the +** number of rows in the table, except for partial indices.) The second +** integer is the average number of rows in the index that have the same +** value in the first column of the index. The third integer is the average +** number of rows in the index that have the same value for the first two +** columns. The N-th integer (for N>1) is the average number of rows in +** the index which have the same value for the first N-1 columns. For +** a K-column index, there will be K+1 integers in the stat column. If +** the index is unique, then the last integer will be 1. +** +** The list of integers in the stat column can optionally be followed +** by the keyword "unordered". The "unordered" keyword, if it is present, +** must be separated from the last integer by a single space. If the +** "unordered" keyword is present, then the query planner assumes that +** the index is unordered and will not use the index for a range query. +** +** If the sqlite_stat1.idx column is NULL, then the sqlite_stat1.stat +** column contains a single integer which is the (estimated) number of +** rows in the table identified by sqlite_stat1.tbl. +** +** Format of sqlite_stat2: +** +** The sqlite_stat2 is only created and is only used if SQLite is compiled +** with SQLITE_ENABLE_STAT2 and if the SQLite version number is between +** 3.6.18 and 3.7.8. The "stat2" table contains additional information +** about the distribution of keys within an index. The index is identified by +** the "idx" column and the "tbl" column is the name of the table to which +** the index belongs. There are usually 10 rows in the sqlite_stat2 +** table for each index. +** +** The sqlite_stat2 entries for an index that have sampleno between 0 and 9 +** inclusive are samples of the left-most key value in the index taken at +** evenly spaced points along the index. Let the number of samples be S +** (10 in the standard build) and let C be the number of rows in the index. +** Then the sampled rows are given by: +** +** rownumber = (i*C*2 + C)/(S*2) +** +** For i between 0 and S-1. Conceptually, the index space is divided into +** S uniform buckets and the samples are the middle row from each bucket. +** +** The format for sqlite_stat2 is recorded here for legacy reference. This +** version of SQLite does not support sqlite_stat2. It neither reads nor +** writes the sqlite_stat2 table. This version of SQLite only supports +** sqlite_stat3. +** +** Format for sqlite_stat3: +** +** The sqlite_stat3 format is a subset of sqlite_stat4. Hence, the +** sqlite_stat4 format will be described first. Further information +** about sqlite_stat3 follows the sqlite_stat4 description. +** +** Format for sqlite_stat4: +** +** As with sqlite_stat2, the sqlite_stat4 table contains histogram data +** to aid the query planner in choosing good indices based on the values +** that indexed columns are compared against in the WHERE clauses of +** queries. +** +** The sqlite_stat4 table contains multiple entries for each index. +** The idx column names the index and the tbl column is the table of the +** index. If the idx and tbl columns are the same, then the sample is +** of the INTEGER PRIMARY KEY. The sample column is a blob which is the +** binary encoding of a key from the index. The nEq column is a +** list of integers. The first integer is the approximate number +** of entries in the index whose left-most column exactly matches +** the left-most column of the sample. The second integer in nEq +** is the approximate number of entries in the index where the +** first two columns match the first two columns of the sample. +** And so forth. nLt is another list of integers that show the approximate +** number of entries that are strictly less than the sample. The first +** integer in nLt contains the number of entries in the index where the +** left-most column is less than the left-most column of the sample. +** The K-th integer in the nLt entry is the number of index entries +** where the first K columns are less than the first K columns of the +** sample. The nDLt column is like nLt except that it contains the +** number of distinct entries in the index that are less than the +** sample. +** +** There can be an arbitrary number of sqlite_stat4 entries per index. +** The ANALYZE command will typically generate sqlite_stat4 tables +** that contain between 10 and 40 samples which are distributed across +** the key space, though not uniformly, and which include samples with +** large nEq values. +** +** Format for sqlite_stat3 redux: +** +** The sqlite_stat3 table is like sqlite_stat4 except that it only +** looks at the left-most column of the index. The sqlite_stat3.sample +** column contains the actual value of the left-most column instead +** of a blob encoding of the complete index key as is found in +** sqlite_stat4.sample. The nEq, nLt, and nDLt entries of sqlite_stat3 +** all contain just a single integer which is the same as the first +** integer in the equivalent columns in sqlite_stat4. +*/ +#ifndef SQLITE_OMIT_ANALYZE +#include "sqliteInt.h" + +#if defined(SQLITE_ENABLE_STAT4) +# define IsStat4 1 +#else +# define IsStat4 0 +# undef SQLITE_STAT4_SAMPLES +# define SQLITE_STAT4_SAMPLES 1 +#endif + +/* +** This routine generates code that opens the sqlite_statN tables. +** The sqlite_stat1 table is always relevant. sqlite_stat2 is now +** obsolete. sqlite_stat3 and sqlite_stat4 are only opened when +** appropriate compile-time options are provided. +** +** If the sqlite_statN tables do not previously exist, it is created. +** +** Argument zWhere may be a pointer to a buffer containing a table name, +** or it may be a NULL pointer. If it is not NULL, then all entries in +** the sqlite_statN tables associated with the named table are deleted. +** If zWhere==0, then code is generated to delete all stat table entries. +*/ +static void openStatTable( + Parse *pParse, /* Parsing context */ + int iDb, /* The database we are looking in */ + int iStatCur, /* Open the sqlite_stat1 table on this cursor */ + const char *zWhere, /* Delete entries for this table or index */ + const char *zWhereType /* Either "tbl" or "idx" */ +){ + static const struct { + const char *zName; + const char *zCols; + } aTable[] = { + { "sqlite_stat1", "tbl,idx,stat" }, +#if defined(SQLITE_ENABLE_STAT4) + { "sqlite_stat4", "tbl,idx,neq,nlt,ndlt,sample" }, +#else + { "sqlite_stat4", 0 }, +#endif + { "sqlite_stat3", 0 }, + }; + int i; + sqlite3 *db = pParse->db; + Db *pDb; + Vdbe *v = sqlite3GetVdbe(pParse); + u32 aRoot[ArraySize(aTable)]; + u8 aCreateTbl[ArraySize(aTable)]; +#ifdef SQLITE_ENABLE_STAT4 + const int nToOpen = OptimizationEnabled(db,SQLITE_Stat4) ? 2 : 1; +#else + const int nToOpen = 1; +#endif + + if( v==0 ) return; + assert( sqlite3BtreeHoldsAllMutexes(db) ); + assert( sqlite3VdbeDb(v)==db ); + pDb = &db->aDb[iDb]; + + /* Create new statistic tables if they do not exist, or clear them + ** if they do already exist. + */ + for(i=0; i<ArraySize(aTable); i++){ + const char *zTab = aTable[i].zName; + Table *pStat; + aCreateTbl[i] = 0; + if( (pStat = sqlite3FindTable(db, zTab, pDb->zDbSName))==0 ){ + if( i<nToOpen ){ + /* The sqlite_statN table does not exist. Create it. Note that a + ** side-effect of the CREATE TABLE statement is to leave the rootpage + ** of the new table in register pParse->regRoot. This is important + ** because the OpenWrite opcode below will be needing it. */ + sqlite3NestedParse(pParse, + "CREATE TABLE %Q.%s(%s)", pDb->zDbSName, zTab, aTable[i].zCols + ); + aRoot[i] = (u32)pParse->regRoot; + aCreateTbl[i] = OPFLAG_P2ISREG; + } + }else{ + /* The table already exists. If zWhere is not NULL, delete all entries + ** associated with the table zWhere. If zWhere is NULL, delete the + ** entire contents of the table. */ + aRoot[i] = pStat->tnum; + sqlite3TableLock(pParse, iDb, aRoot[i], 1, zTab); + if( zWhere ){ + sqlite3NestedParse(pParse, + "DELETE FROM %Q.%s WHERE %s=%Q", + pDb->zDbSName, zTab, zWhereType, zWhere + ); +#ifdef SQLITE_ENABLE_PREUPDATE_HOOK + }else if( db->xPreUpdateCallback ){ + sqlite3NestedParse(pParse, "DELETE FROM %Q.%s", pDb->zDbSName, zTab); +#endif + }else{ + /* The sqlite_stat[134] table already exists. Delete all rows. */ + sqlite3VdbeAddOp2(v, OP_Clear, (int)aRoot[i], iDb); + } + } + } + + /* Open the sqlite_stat[134] tables for writing. */ + for(i=0; i<nToOpen; i++){ + assert( i<ArraySize(aTable) ); + sqlite3VdbeAddOp4Int(v, OP_OpenWrite, iStatCur+i, (int)aRoot[i], iDb, 3); + sqlite3VdbeChangeP5(v, aCreateTbl[i]); + VdbeComment((v, aTable[i].zName)); + } +} + +/* +** Recommended number of samples for sqlite_stat4 +*/ +#ifndef SQLITE_STAT4_SAMPLES +# define SQLITE_STAT4_SAMPLES 24 +#endif + +/* +** Three SQL functions - stat_init(), stat_push(), and stat_get() - +** share an instance of the following structure to hold their state +** information. +*/ +typedef struct StatAccum StatAccum; +typedef struct StatSample StatSample; +struct StatSample { + tRowcnt *anDLt; /* sqlite_stat4.nDLt */ +#ifdef SQLITE_ENABLE_STAT4 + tRowcnt *anEq; /* sqlite_stat4.nEq */ + tRowcnt *anLt; /* sqlite_stat4.nLt */ + union { + i64 iRowid; /* Rowid in main table of the key */ + u8 *aRowid; /* Key for WITHOUT ROWID tables */ + } u; + u32 nRowid; /* Sizeof aRowid[] */ + u8 isPSample; /* True if a periodic sample */ + int iCol; /* If !isPSample, the reason for inclusion */ + u32 iHash; /* Tiebreaker hash */ +#endif +}; +struct StatAccum { + sqlite3 *db; /* Database connection, for malloc() */ + tRowcnt nEst; /* Estimated number of rows */ + tRowcnt nRow; /* Number of rows visited so far */ + int nLimit; /* Analysis row-scan limit */ + int nCol; /* Number of columns in index + pk/rowid */ + int nKeyCol; /* Number of index columns w/o the pk/rowid */ + u8 nSkipAhead; /* Number of times of skip-ahead */ + StatSample current; /* Current row as a StatSample */ +#ifdef SQLITE_ENABLE_STAT4 + tRowcnt nPSample; /* How often to do a periodic sample */ + int mxSample; /* Maximum number of samples to accumulate */ + u32 iPrn; /* Pseudo-random number used for sampling */ + StatSample *aBest; /* Array of nCol best samples */ + int iMin; /* Index in a[] of entry with minimum score */ + int nSample; /* Current number of samples */ + int nMaxEqZero; /* Max leading 0 in anEq[] for any a[] entry */ + int iGet; /* Index of current sample accessed by stat_get() */ + StatSample *a; /* Array of mxSample StatSample objects */ +#endif +}; + +/* Reclaim memory used by a StatSample +*/ +#ifdef SQLITE_ENABLE_STAT4 +static void sampleClear(sqlite3 *db, StatSample *p){ + assert( db!=0 ); + if( p->nRowid ){ + sqlite3DbFree(db, p->u.aRowid); + p->nRowid = 0; + } +} +#endif + +/* Initialize the BLOB value of a ROWID +*/ +#ifdef SQLITE_ENABLE_STAT4 +static void sampleSetRowid(sqlite3 *db, StatSample *p, int n, const u8 *pData){ + assert( db!=0 ); + if( p->nRowid ) sqlite3DbFree(db, p->u.aRowid); + p->u.aRowid = sqlite3DbMallocRawNN(db, n); + if( p->u.aRowid ){ + p->nRowid = n; + memcpy(p->u.aRowid, pData, n); + }else{ + p->nRowid = 0; + } +} +#endif + +/* Initialize the INTEGER value of a ROWID. +*/ +#ifdef SQLITE_ENABLE_STAT4 +static void sampleSetRowidInt64(sqlite3 *db, StatSample *p, i64 iRowid){ + assert( db!=0 ); + if( p->nRowid ) sqlite3DbFree(db, p->u.aRowid); + p->nRowid = 0; + p->u.iRowid = iRowid; +} +#endif + + +/* +** Copy the contents of object (*pFrom) into (*pTo). +*/ +#ifdef SQLITE_ENABLE_STAT4 +static void sampleCopy(StatAccum *p, StatSample *pTo, StatSample *pFrom){ + pTo->isPSample = pFrom->isPSample; + pTo->iCol = pFrom->iCol; + pTo->iHash = pFrom->iHash; + memcpy(pTo->anEq, pFrom->anEq, sizeof(tRowcnt)*p->nCol); + memcpy(pTo->anLt, pFrom->anLt, sizeof(tRowcnt)*p->nCol); + memcpy(pTo->anDLt, pFrom->anDLt, sizeof(tRowcnt)*p->nCol); + if( pFrom->nRowid ){ + sampleSetRowid(p->db, pTo, pFrom->nRowid, pFrom->u.aRowid); + }else{ + sampleSetRowidInt64(p->db, pTo, pFrom->u.iRowid); + } +} +#endif + +/* +** Reclaim all memory of a StatAccum structure. +*/ +static void statAccumDestructor(void *pOld){ + StatAccum *p = (StatAccum*)pOld; +#ifdef SQLITE_ENABLE_STAT4 + if( p->mxSample ){ + int i; + for(i=0; i<p->nCol; i++) sampleClear(p->db, p->aBest+i); + for(i=0; i<p->mxSample; i++) sampleClear(p->db, p->a+i); + sampleClear(p->db, &p->current); + } +#endif + sqlite3DbFree(p->db, p); +} + +/* +** Implementation of the stat_init(N,K,C,L) SQL function. The four parameters +** are: +** N: The number of columns in the index including the rowid/pk (note 1) +** K: The number of columns in the index excluding the rowid/pk. +** C: Estimated number of rows in the index +** L: A limit on the number of rows to scan, or 0 for no-limit +** +** Note 1: In the special case of the covering index that implements a +** WITHOUT ROWID table, N is the number of PRIMARY KEY columns, not the +** total number of columns in the table. +** +** For indexes on ordinary rowid tables, N==K+1. But for indexes on +** WITHOUT ROWID tables, N=K+P where P is the number of columns in the +** PRIMARY KEY of the table. The covering index that implements the +** original WITHOUT ROWID table as N==K as a special case. +** +** This routine allocates the StatAccum object in heap memory. The return +** value is a pointer to the StatAccum object. The datatype of the +** return value is BLOB, but it is really just a pointer to the StatAccum +** object. +*/ +static void statInit( + sqlite3_context *context, + int argc, + sqlite3_value **argv +){ + StatAccum *p; + int nCol; /* Number of columns in index being sampled */ + int nKeyCol; /* Number of key columns */ + int nColUp; /* nCol rounded up for alignment */ + int n; /* Bytes of space to allocate */ + sqlite3 *db = sqlite3_context_db_handle(context); /* Database connection */ +#ifdef SQLITE_ENABLE_STAT4 + /* Maximum number of samples. 0 if STAT4 data is not collected */ + int mxSample = OptimizationEnabled(db,SQLITE_Stat4) ?SQLITE_STAT4_SAMPLES :0; +#endif + + /* Decode the three function arguments */ + UNUSED_PARAMETER(argc); + nCol = sqlite3_value_int(argv[0]); + assert( nCol>0 ); + nColUp = sizeof(tRowcnt)<8 ? (nCol+1)&~1 : nCol; + nKeyCol = sqlite3_value_int(argv[1]); + assert( nKeyCol<=nCol ); + assert( nKeyCol>0 ); + + /* Allocate the space required for the StatAccum object */ + n = sizeof(*p) + + sizeof(tRowcnt)*nColUp; /* StatAccum.anDLt */ +#ifdef SQLITE_ENABLE_STAT4 + n += sizeof(tRowcnt)*nColUp; /* StatAccum.anEq */ + if( mxSample ){ + n += sizeof(tRowcnt)*nColUp /* StatAccum.anLt */ + + sizeof(StatSample)*(nCol+mxSample) /* StatAccum.aBest[], a[] */ + + sizeof(tRowcnt)*3*nColUp*(nCol+mxSample); + } +#endif + p = sqlite3DbMallocZero(db, n); + if( p==0 ){ + sqlite3_result_error_nomem(context); + return; + } + + p->db = db; + p->nEst = sqlite3_value_int64(argv[2]); + p->nRow = 0; + p->nLimit = sqlite3_value_int64(argv[3]); + p->nCol = nCol; + p->nKeyCol = nKeyCol; + p->nSkipAhead = 0; + p->current.anDLt = (tRowcnt*)&p[1]; + +#ifdef SQLITE_ENABLE_STAT4 + p->current.anEq = &p->current.anDLt[nColUp]; + p->mxSample = p->nLimit==0 ? mxSample : 0; + if( mxSample ){ + u8 *pSpace; /* Allocated space not yet assigned */ + int i; /* Used to iterate through p->aSample[] */ + + p->iGet = -1; + p->nPSample = (tRowcnt)(p->nEst/(mxSample/3+1) + 1); + p->current.anLt = &p->current.anEq[nColUp]; + p->iPrn = 0x689e962d*(u32)nCol ^ 0xd0944565*(u32)sqlite3_value_int(argv[2]); + + /* Set up the StatAccum.a[] and aBest[] arrays */ + p->a = (struct StatSample*)&p->current.anLt[nColUp]; + p->aBest = &p->a[mxSample]; + pSpace = (u8*)(&p->a[mxSample+nCol]); + for(i=0; i<(mxSample+nCol); i++){ + p->a[i].anEq = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nColUp); + p->a[i].anLt = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nColUp); + p->a[i].anDLt = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nColUp); + } + assert( (pSpace - (u8*)p)==n ); + + for(i=0; i<nCol; i++){ + p->aBest[i].iCol = i; + } + } +#endif + + /* Return a pointer to the allocated object to the caller. Note that + ** only the pointer (the 2nd parameter) matters. The size of the object + ** (given by the 3rd parameter) is never used and can be any positive + ** value. */ + sqlite3_result_blob(context, p, sizeof(*p), statAccumDestructor); +} +static const FuncDef statInitFuncdef = { + 4, /* nArg */ + SQLITE_UTF8, /* funcFlags */ + 0, /* pUserData */ + 0, /* pNext */ + statInit, /* xSFunc */ + 0, /* xFinalize */ + 0, 0, /* xValue, xInverse */ + "stat_init", /* zName */ + {0} +}; + +#ifdef SQLITE_ENABLE_STAT4 +/* +** pNew and pOld are both candidate non-periodic samples selected for +** the same column (pNew->iCol==pOld->iCol). Ignoring this column and +** considering only any trailing columns and the sample hash value, this +** function returns true if sample pNew is to be preferred over pOld. +** In other words, if we assume that the cardinalities of the selected +** column for pNew and pOld are equal, is pNew to be preferred over pOld. +** +** This function assumes that for each argument sample, the contents of +** the anEq[] array from pSample->anEq[pSample->iCol+1] onwards are valid. +*/ +static int sampleIsBetterPost( + StatAccum *pAccum, + StatSample *pNew, + StatSample *pOld +){ + int nCol = pAccum->nCol; + int i; + assert( pNew->iCol==pOld->iCol ); + for(i=pNew->iCol+1; i<nCol; i++){ + if( pNew->anEq[i]>pOld->anEq[i] ) return 1; + if( pNew->anEq[i]<pOld->anEq[i] ) return 0; + } + if( pNew->iHash>pOld->iHash ) return 1; + return 0; +} +#endif + +#ifdef SQLITE_ENABLE_STAT4 +/* +** Return true if pNew is to be preferred over pOld. +** +** This function assumes that for each argument sample, the contents of +** the anEq[] array from pSample->anEq[pSample->iCol] onwards are valid. +*/ +static int sampleIsBetter( + StatAccum *pAccum, + StatSample *pNew, + StatSample *pOld +){ + tRowcnt nEqNew = pNew->anEq[pNew->iCol]; + tRowcnt nEqOld = pOld->anEq[pOld->iCol]; + + assert( pOld->isPSample==0 && pNew->isPSample==0 ); + assert( IsStat4 || (pNew->iCol==0 && pOld->iCol==0) ); + + if( (nEqNew>nEqOld) ) return 1; + if( nEqNew==nEqOld ){ + if( pNew->iCol<pOld->iCol ) return 1; + return (pNew->iCol==pOld->iCol && sampleIsBetterPost(pAccum, pNew, pOld)); + } + return 0; +} + +/* +** Copy the contents of sample *pNew into the p->a[] array. If necessary, +** remove the least desirable sample from p->a[] to make room. +*/ +static void sampleInsert(StatAccum *p, StatSample *pNew, int nEqZero){ + StatSample *pSample = 0; + int i; + + assert( IsStat4 || nEqZero==0 ); + + /* StatAccum.nMaxEqZero is set to the maximum number of leading 0 + ** values in the anEq[] array of any sample in StatAccum.a[]. In + ** other words, if nMaxEqZero is n, then it is guaranteed that there + ** are no samples with StatSample.anEq[m]==0 for (m>=n). */ + if( nEqZero>p->nMaxEqZero ){ + p->nMaxEqZero = nEqZero; + } + if( pNew->isPSample==0 ){ + StatSample *pUpgrade = 0; + assert( pNew->anEq[pNew->iCol]>0 ); + + /* This sample is being added because the prefix that ends in column + ** iCol occurs many times in the table. However, if we have already + ** added a sample that shares this prefix, there is no need to add + ** this one. Instead, upgrade the priority of the highest priority + ** existing sample that shares this prefix. */ + for(i=p->nSample-1; i>=0; i--){ + StatSample *pOld = &p->a[i]; + if( pOld->anEq[pNew->iCol]==0 ){ + if( pOld->isPSample ) return; + assert( pOld->iCol>pNew->iCol ); + assert( sampleIsBetter(p, pNew, pOld) ); + if( pUpgrade==0 || sampleIsBetter(p, pOld, pUpgrade) ){ + pUpgrade = pOld; + } + } + } + if( pUpgrade ){ + pUpgrade->iCol = pNew->iCol; + pUpgrade->anEq[pUpgrade->iCol] = pNew->anEq[pUpgrade->iCol]; + goto find_new_min; + } + } + + /* If necessary, remove sample iMin to make room for the new sample. */ + if( p->nSample>=p->mxSample ){ + StatSample *pMin = &p->a[p->iMin]; + tRowcnt *anEq = pMin->anEq; + tRowcnt *anLt = pMin->anLt; + tRowcnt *anDLt = pMin->anDLt; + sampleClear(p->db, pMin); + memmove(pMin, &pMin[1], sizeof(p->a[0])*(p->nSample-p->iMin-1)); + pSample = &p->a[p->nSample-1]; + pSample->nRowid = 0; + pSample->anEq = anEq; + pSample->anDLt = anDLt; + pSample->anLt = anLt; + p->nSample = p->mxSample-1; + } + + /* The "rows less-than" for the rowid column must be greater than that + ** for the last sample in the p->a[] array. Otherwise, the samples would + ** be out of order. */ + assert( p->nSample==0 + || pNew->anLt[p->nCol-1] > p->a[p->nSample-1].anLt[p->nCol-1] ); + + /* Insert the new sample */ + pSample = &p->a[p->nSample]; + sampleCopy(p, pSample, pNew); + p->nSample++; + + /* Zero the first nEqZero entries in the anEq[] array. */ + memset(pSample->anEq, 0, sizeof(tRowcnt)*nEqZero); + +find_new_min: + if( p->nSample>=p->mxSample ){ + int iMin = -1; + for(i=0; i<p->mxSample; i++){ + if( p->a[i].isPSample ) continue; + if( iMin<0 || sampleIsBetter(p, &p->a[iMin], &p->a[i]) ){ + iMin = i; + } + } + assert( iMin>=0 ); + p->iMin = iMin; + } +} +#endif /* SQLITE_ENABLE_STAT4 */ + +#ifdef SQLITE_ENABLE_STAT4 +/* +** Field iChng of the index being scanned has changed. So at this point +** p->current contains a sample that reflects the previous row of the +** index. The value of anEq[iChng] and subsequent anEq[] elements are +** correct at this point. +*/ +static void samplePushPrevious(StatAccum *p, int iChng){ + int i; + + /* Check if any samples from the aBest[] array should be pushed + ** into IndexSample.a[] at this point. */ + for(i=(p->nCol-2); i>=iChng; i--){ + StatSample *pBest = &p->aBest[i]; + pBest->anEq[i] = p->current.anEq[i]; + if( p->nSample<p->mxSample || sampleIsBetter(p, pBest, &p->a[p->iMin]) ){ + sampleInsert(p, pBest, i); + } + } + + /* Check that no sample contains an anEq[] entry with an index of + ** p->nMaxEqZero or greater set to zero. */ + for(i=p->nSample-1; i>=0; i--){ + int j; + for(j=p->nMaxEqZero; j<p->nCol; j++) assert( p->a[i].anEq[j]>0 ); + } + + /* Update the anEq[] fields of any samples already collected. */ + if( iChng<p->nMaxEqZero ){ + for(i=p->nSample-1; i>=0; i--){ + int j; + for(j=iChng; j<p->nCol; j++){ + if( p->a[i].anEq[j]==0 ) p->a[i].anEq[j] = p->current.anEq[j]; + } + } + p->nMaxEqZero = iChng; + } +} +#endif /* SQLITE_ENABLE_STAT4 */ + +/* +** Implementation of the stat_push SQL function: stat_push(P,C,R) +** Arguments: +** +** P Pointer to the StatAccum object created by stat_init() +** C Index of left-most column to differ from previous row +** R Rowid for the current row. Might be a key record for +** WITHOUT ROWID tables. +** +** The purpose of this routine is to collect statistical data and/or +** samples from the index being analyzed into the StatAccum object. +** The stat_get() SQL function will be used afterwards to +** retrieve the information gathered. +** +** This SQL function usually returns NULL, but might return an integer +** if it wants the byte-code to do special processing. +** +** The R parameter is only used for STAT4 +*/ +static void statPush( + sqlite3_context *context, + int argc, + sqlite3_value **argv +){ + int i; + + /* The three function arguments */ + StatAccum *p = (StatAccum*)sqlite3_value_blob(argv[0]); + int iChng = sqlite3_value_int(argv[1]); + + UNUSED_PARAMETER( argc ); + UNUSED_PARAMETER( context ); + assert( p->nCol>0 ); + assert( iChng<p->nCol ); + + if( p->nRow==0 ){ + /* This is the first call to this function. Do initialization. */ +#ifdef SQLITE_ENABLE_STAT4 + for(i=0; i<p->nCol; i++) p->current.anEq[i] = 1; +#endif + }else{ + /* Second and subsequent calls get processed here */ +#ifdef SQLITE_ENABLE_STAT4 + if( p->mxSample ) samplePushPrevious(p, iChng); +#endif + + /* Update anDLt[], anLt[] and anEq[] to reflect the values that apply + ** to the current row of the index. */ +#ifdef SQLITE_ENABLE_STAT4 + for(i=0; i<iChng; i++){ + p->current.anEq[i]++; + } +#endif + for(i=iChng; i<p->nCol; i++){ + p->current.anDLt[i]++; +#ifdef SQLITE_ENABLE_STAT4 + if( p->mxSample ) p->current.anLt[i] += p->current.anEq[i]; + p->current.anEq[i] = 1; +#endif + } + } + + p->nRow++; +#ifdef SQLITE_ENABLE_STAT4 + if( p->mxSample ){ + tRowcnt nLt; + if( sqlite3_value_type(argv[2])==SQLITE_INTEGER ){ + sampleSetRowidInt64(p->db, &p->current, sqlite3_value_int64(argv[2])); + }else{ + sampleSetRowid(p->db, &p->current, sqlite3_value_bytes(argv[2]), + sqlite3_value_blob(argv[2])); + } + p->current.iHash = p->iPrn = p->iPrn*1103515245 + 12345; + + nLt = p->current.anLt[p->nCol-1]; + /* Check if this is to be a periodic sample. If so, add it. */ + if( (nLt/p->nPSample)!=(nLt+1)/p->nPSample ){ + p->current.isPSample = 1; + p->current.iCol = 0; + sampleInsert(p, &p->current, p->nCol-1); + p->current.isPSample = 0; + } + + /* Update the aBest[] array. */ + for(i=0; i<(p->nCol-1); i++){ + p->current.iCol = i; + if( i>=iChng || sampleIsBetterPost(p, &p->current, &p->aBest[i]) ){ + sampleCopy(p, &p->aBest[i], &p->current); + } + } + }else +#endif + if( p->nLimit && p->nRow>(tRowcnt)p->nLimit*(p->nSkipAhead+1) ){ + p->nSkipAhead++; + sqlite3_result_int(context, p->current.anDLt[0]>0); + } +} + +static const FuncDef statPushFuncdef = { + 2+IsStat4, /* nArg */ + SQLITE_UTF8, /* funcFlags */ + 0, /* pUserData */ + 0, /* pNext */ + statPush, /* xSFunc */ + 0, /* xFinalize */ + 0, 0, /* xValue, xInverse */ + "stat_push", /* zName */ + {0} +}; + +#define STAT_GET_STAT1 0 /* "stat" column of stat1 table */ +#define STAT_GET_ROWID 1 /* "rowid" column of stat[34] entry */ +#define STAT_GET_NEQ 2 /* "neq" column of stat[34] entry */ +#define STAT_GET_NLT 3 /* "nlt" column of stat[34] entry */ +#define STAT_GET_NDLT 4 /* "ndlt" column of stat[34] entry */ + +/* +** Implementation of the stat_get(P,J) SQL function. This routine is +** used to query statistical information that has been gathered into +** the StatAccum object by prior calls to stat_push(). The P parameter +** has type BLOB but it is really just a pointer to the StatAccum object. +** The content to returned is determined by the parameter J +** which is one of the STAT_GET_xxxx values defined above. +** +** The stat_get(P,J) function is not available to generic SQL. It is +** inserted as part of a manually constructed bytecode program. (See +** the callStatGet() routine below.) It is guaranteed that the P +** parameter will always be a pointer to a StatAccum object, never a +** NULL. +** +** If STAT4 is not enabled, then J is always +** STAT_GET_STAT1 and is hence omitted and this routine becomes +** a one-parameter function, stat_get(P), that always returns the +** stat1 table entry information. +*/ +static void statGet( + sqlite3_context *context, + int argc, + sqlite3_value **argv +){ + StatAccum *p = (StatAccum*)sqlite3_value_blob(argv[0]); +#ifdef SQLITE_ENABLE_STAT4 + /* STAT4 has a parameter on this routine. */ + int eCall = sqlite3_value_int(argv[1]); + assert( argc==2 ); + assert( eCall==STAT_GET_STAT1 || eCall==STAT_GET_NEQ + || eCall==STAT_GET_ROWID || eCall==STAT_GET_NLT + || eCall==STAT_GET_NDLT + ); + assert( eCall==STAT_GET_STAT1 || p->mxSample ); + if( eCall==STAT_GET_STAT1 ) +#else + assert( argc==1 ); +#endif + { + /* Return the value to store in the "stat" column of the sqlite_stat1 + ** table for this index. + ** + ** The value is a string composed of a list of integers describing + ** the index. The first integer in the list is the total number of + ** entries in the index. There is one additional integer in the list + ** for each indexed column. This additional integer is an estimate of + ** the number of rows matched by a equality query on the index using + ** a key with the corresponding number of fields. In other words, + ** if the index is on columns (a,b) and the sqlite_stat1 value is + ** "100 10 2", then SQLite estimates that: + ** + ** * the index contains 100 rows, + ** * "WHERE a=?" matches 10 rows, and + ** * "WHERE a=? AND b=?" matches 2 rows. + ** + ** If D is the count of distinct values and K is the total number of + ** rows, then each estimate is usually computed as: + ** + ** I = (K+D-1)/D + ** + ** In other words, I is K/D rounded up to the next whole integer. + ** However, if I is between 1.0 and 1.1 (in other words if I is + ** close to 1.0 but just a little larger) then do not round up but + ** instead keep the I value at 1.0. + */ + sqlite3_str sStat; /* Text of the constructed "stat" line */ + int i; /* Loop counter */ + + sqlite3StrAccumInit(&sStat, 0, 0, 0, (p->nKeyCol+1)*100); + sqlite3_str_appendf(&sStat, "%llu", + p->nSkipAhead ? (u64)p->nEst : (u64)p->nRow); + for(i=0; i<p->nKeyCol; i++){ + u64 nDistinct = p->current.anDLt[i] + 1; + u64 iVal = (p->nRow + nDistinct - 1) / nDistinct; + if( iVal==2 && p->nRow*10 <= nDistinct*11 ) iVal = 1; + sqlite3_str_appendf(&sStat, " %llu", iVal); +#ifdef SQLITE_ENABLE_STAT4 + assert( p->current.anEq[i] ); +#endif + } + sqlite3ResultStrAccum(context, &sStat); + } +#ifdef SQLITE_ENABLE_STAT4 + else if( eCall==STAT_GET_ROWID ){ + if( p->iGet<0 ){ + samplePushPrevious(p, 0); + p->iGet = 0; + } + if( p->iGet<p->nSample ){ + StatSample *pS = p->a + p->iGet; + if( pS->nRowid==0 ){ + sqlite3_result_int64(context, pS->u.iRowid); + }else{ + sqlite3_result_blob(context, pS->u.aRowid, pS->nRowid, + SQLITE_TRANSIENT); + } + } + }else{ + tRowcnt *aCnt = 0; + sqlite3_str sStat; + int i; + + assert( p->iGet<p->nSample ); + switch( eCall ){ + case STAT_GET_NEQ: aCnt = p->a[p->iGet].anEq; break; + case STAT_GET_NLT: aCnt = p->a[p->iGet].anLt; break; + default: { + aCnt = p->a[p->iGet].anDLt; + p->iGet++; + break; + } + } + sqlite3StrAccumInit(&sStat, 0, 0, 0, p->nCol*100); + for(i=0; i<p->nCol; i++){ + sqlite3_str_appendf(&sStat, "%llu ", (u64)aCnt[i]); + } + if( sStat.nChar ) sStat.nChar--; + sqlite3ResultStrAccum(context, &sStat); + } +#endif /* SQLITE_ENABLE_STAT4 */ +#ifndef SQLITE_DEBUG + UNUSED_PARAMETER( argc ); +#endif +} +static const FuncDef statGetFuncdef = { + 1+IsStat4, /* nArg */ + SQLITE_UTF8, /* funcFlags */ + 0, /* pUserData */ + 0, /* pNext */ + statGet, /* xSFunc */ + 0, /* xFinalize */ + 0, 0, /* xValue, xInverse */ + "stat_get", /* zName */ + {0} +}; + +static void callStatGet(Parse *pParse, int regStat, int iParam, int regOut){ +#ifdef SQLITE_ENABLE_STAT4 + sqlite3VdbeAddOp2(pParse->pVdbe, OP_Integer, iParam, regStat+1); +#elif SQLITE_DEBUG + assert( iParam==STAT_GET_STAT1 ); +#else + UNUSED_PARAMETER( iParam ); +#endif + assert( regOut!=regStat && regOut!=regStat+1 ); + sqlite3VdbeAddFunctionCall(pParse, 0, regStat, regOut, 1+IsStat4, + &statGetFuncdef, 0); +} + +#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS +/* Add a comment to the most recent VDBE opcode that is the name +** of the k-th column of the pIdx index. +*/ +static void analyzeVdbeCommentIndexWithColumnName( + Vdbe *v, /* Prepared statement under construction */ + Index *pIdx, /* Index whose column is being loaded */ + int k /* Which column index */ +){ + int i; /* Index of column in the table */ + assert( k>=0 && k<pIdx->nColumn ); + i = pIdx->aiColumn[k]; + if( NEVER(i==XN_ROWID) ){ + VdbeComment((v,"%s.rowid",pIdx->zName)); + }else if( i==XN_EXPR ){ + assert( pIdx->bHasExpr ); + VdbeComment((v,"%s.expr(%d)",pIdx->zName, k)); + }else{ + VdbeComment((v,"%s.%s", pIdx->zName, pIdx->pTable->aCol[i].zCnName)); + } +} +#else +# define analyzeVdbeCommentIndexWithColumnName(a,b,c) +#endif /* SQLITE_DEBUG */ + +/* +** Generate code to do an analysis of all indices associated with +** a single table. +*/ +static void analyzeOneTable( + Parse *pParse, /* Parser context */ + Table *pTab, /* Table whose indices are to be analyzed */ + Index *pOnlyIdx, /* If not NULL, only analyze this one index */ + int iStatCur, /* Index of VdbeCursor that writes the sqlite_stat1 table */ + int iMem, /* Available memory locations begin here */ + int iTab /* Next available cursor */ +){ + sqlite3 *db = pParse->db; /* Database handle */ + Index *pIdx; /* An index to being analyzed */ + int iIdxCur; /* Cursor open on index being analyzed */ + int iTabCur; /* Table cursor */ + Vdbe *v; /* The virtual machine being built up */ + int i; /* Loop counter */ + int jZeroRows = -1; /* Jump from here if number of rows is zero */ + int iDb; /* Index of database containing pTab */ + u8 needTableCnt = 1; /* True to count the table */ + int regNewRowid = iMem++; /* Rowid for the inserted record */ + int regStat = iMem++; /* Register to hold StatAccum object */ + int regChng = iMem++; /* Index of changed index field */ + int regRowid = iMem++; /* Rowid argument passed to stat_push() */ + int regTemp = iMem++; /* Temporary use register */ + int regTemp2 = iMem++; /* Second temporary use register */ + int regTabname = iMem++; /* Register containing table name */ + int regIdxname = iMem++; /* Register containing index name */ + int regStat1 = iMem++; /* Value for the stat column of sqlite_stat1 */ + int regPrev = iMem; /* MUST BE LAST (see below) */ +#ifdef SQLITE_ENABLE_STAT4 + int doOnce = 1; /* Flag for a one-time computation */ +#endif +#ifdef SQLITE_ENABLE_PREUPDATE_HOOK + Table *pStat1 = 0; +#endif + + sqlite3TouchRegister(pParse, iMem); + assert( sqlite3NoTempsInRange(pParse, regNewRowid, iMem) ); + v = sqlite3GetVdbe(pParse); + if( v==0 || NEVER(pTab==0) ){ + return; + } + if( !IsOrdinaryTable(pTab) ){ + /* Do not gather statistics on views or virtual tables */ + return; + } + if( sqlite3_strlike("sqlite\\_%", pTab->zName, '\\')==0 ){ + /* Do not gather statistics on system tables */ + return; + } + assert( sqlite3BtreeHoldsAllMutexes(db) ); + iDb = sqlite3SchemaToIndex(db, pTab->pSchema); + assert( iDb>=0 ); + assert( sqlite3SchemaMutexHeld(db, iDb, 0) ); +#ifndef SQLITE_OMIT_AUTHORIZATION + if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0, + db->aDb[iDb].zDbSName ) ){ + return; + } +#endif + +#ifdef SQLITE_ENABLE_PREUPDATE_HOOK + if( db->xPreUpdateCallback ){ + pStat1 = (Table*)sqlite3DbMallocZero(db, sizeof(Table) + 13); + if( pStat1==0 ) return; + pStat1->zName = (char*)&pStat1[1]; + memcpy(pStat1->zName, "sqlite_stat1", 13); + pStat1->nCol = 3; + pStat1->iPKey = -1; + sqlite3VdbeAddOp4(pParse->pVdbe, OP_Noop, 0, 0, 0,(char*)pStat1,P4_DYNAMIC); + } +#endif + + /* Establish a read-lock on the table at the shared-cache level. + ** Open a read-only cursor on the table. Also allocate a cursor number + ** to use for scanning indexes (iIdxCur). No index cursor is opened at + ** this time though. */ + sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName); + iTabCur = iTab++; + iIdxCur = iTab++; + pParse->nTab = MAX(pParse->nTab, iTab); + sqlite3OpenTable(pParse, iTabCur, iDb, pTab, OP_OpenRead); + sqlite3VdbeLoadString(v, regTabname, pTab->zName); + + for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){ + int nCol; /* Number of columns in pIdx. "N" */ + int addrRewind; /* Address of "OP_Rewind iIdxCur" */ + int addrNextRow; /* Address of "next_row:" */ + const char *zIdxName; /* Name of the index */ + int nColTest; /* Number of columns to test for changes */ + + if( pOnlyIdx && pOnlyIdx!=pIdx ) continue; + if( pIdx->pPartIdxWhere==0 ) needTableCnt = 0; + if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIdx) ){ + nCol = pIdx->nKeyCol; + zIdxName = pTab->zName; + nColTest = nCol - 1; + }else{ + nCol = pIdx->nColumn; + zIdxName = pIdx->zName; + nColTest = pIdx->uniqNotNull ? pIdx->nKeyCol-1 : nCol-1; + } + + /* Populate the register containing the index name. */ + sqlite3VdbeLoadString(v, regIdxname, zIdxName); + VdbeComment((v, "Analysis for %s.%s", pTab->zName, zIdxName)); + + /* + ** Pseudo-code for loop that calls stat_push(): + ** + ** Rewind csr + ** if eof(csr) goto end_of_scan; + ** regChng = 0 + ** goto chng_addr_0; + ** + ** next_row: + ** regChng = 0 + ** if( idx(0) != regPrev(0) ) goto chng_addr_0 + ** regChng = 1 + ** if( idx(1) != regPrev(1) ) goto chng_addr_1 + ** ... + ** regChng = N + ** goto chng_addr_N + ** + ** chng_addr_0: + ** regPrev(0) = idx(0) + ** chng_addr_1: + ** regPrev(1) = idx(1) + ** ... + ** + ** endDistinctTest: + ** regRowid = idx(rowid) + ** stat_push(P, regChng, regRowid) + ** Next csr + ** if !eof(csr) goto next_row; + ** + ** end_of_scan: + */ + + /* Make sure there are enough memory cells allocated to accommodate + ** the regPrev array and a trailing rowid (the rowid slot is required + ** when building a record to insert into the sample column of + ** the sqlite_stat4 table. */ + sqlite3TouchRegister(pParse, regPrev+nColTest); + + /* Open a read-only cursor on the index being analyzed. */ + assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) ); + sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb); + sqlite3VdbeSetP4KeyInfo(pParse, pIdx); + VdbeComment((v, "%s", pIdx->zName)); + + /* Invoke the stat_init() function. The arguments are: + ** + ** (1) the number of columns in the index including the rowid + ** (or for a WITHOUT ROWID table, the number of PK columns), + ** (2) the number of columns in the key without the rowid/pk + ** (3) estimated number of rows in the index, + */ + sqlite3VdbeAddOp2(v, OP_Integer, nCol, regStat+1); + assert( regRowid==regStat+2 ); + sqlite3VdbeAddOp2(v, OP_Integer, pIdx->nKeyCol, regRowid); +#ifdef SQLITE_ENABLE_STAT4 + if( OptimizationEnabled(db, SQLITE_Stat4) ){ + sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regTemp); + addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur); + VdbeCoverage(v); + }else +#endif + { + addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur); + VdbeCoverage(v); + sqlite3VdbeAddOp3(v, OP_Count, iIdxCur, regTemp, 1); + } + assert( regTemp2==regStat+4 ); + sqlite3VdbeAddOp2(v, OP_Integer, db->nAnalysisLimit, regTemp2); + sqlite3VdbeAddFunctionCall(pParse, 0, regStat+1, regStat, 4, + &statInitFuncdef, 0); + + /* Implementation of the following: + ** + ** Rewind csr + ** if eof(csr) goto end_of_scan; + ** regChng = 0 + ** goto next_push_0; + ** + */ + sqlite3VdbeAddOp2(v, OP_Integer, 0, regChng); + addrNextRow = sqlite3VdbeCurrentAddr(v); + + if( nColTest>0 ){ + int endDistinctTest = sqlite3VdbeMakeLabel(pParse); + int *aGotoChng; /* Array of jump instruction addresses */ + aGotoChng = sqlite3DbMallocRawNN(db, sizeof(int)*nColTest); + if( aGotoChng==0 ) continue; + + /* + ** next_row: + ** regChng = 0 + ** if( idx(0) != regPrev(0) ) goto chng_addr_0 + ** regChng = 1 + ** if( idx(1) != regPrev(1) ) goto chng_addr_1 + ** ... + ** regChng = N + ** goto endDistinctTest + */ + sqlite3VdbeAddOp0(v, OP_Goto); + addrNextRow = sqlite3VdbeCurrentAddr(v); + if( nColTest==1 && pIdx->nKeyCol==1 && IsUniqueIndex(pIdx) ){ + /* For a single-column UNIQUE index, once we have found a non-NULL + ** row, we know that all the rest will be distinct, so skip + ** subsequent distinctness tests. */ + sqlite3VdbeAddOp2(v, OP_NotNull, regPrev, endDistinctTest); + VdbeCoverage(v); + } + for(i=0; i<nColTest; i++){ + char *pColl = (char*)sqlite3LocateCollSeq(pParse, pIdx->azColl[i]); + sqlite3VdbeAddOp2(v, OP_Integer, i, regChng); + sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regTemp); + analyzeVdbeCommentIndexWithColumnName(v,pIdx,i); + aGotoChng[i] = + sqlite3VdbeAddOp4(v, OP_Ne, regTemp, 0, regPrev+i, pColl, P4_COLLSEQ); + sqlite3VdbeChangeP5(v, SQLITE_NULLEQ); + VdbeCoverage(v); + } + sqlite3VdbeAddOp2(v, OP_Integer, nColTest, regChng); + sqlite3VdbeGoto(v, endDistinctTest); + + + /* + ** chng_addr_0: + ** regPrev(0) = idx(0) + ** chng_addr_1: + ** regPrev(1) = idx(1) + ** ... + */ + sqlite3VdbeJumpHere(v, addrNextRow-1); + for(i=0; i<nColTest; i++){ + sqlite3VdbeJumpHere(v, aGotoChng[i]); + sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regPrev+i); + analyzeVdbeCommentIndexWithColumnName(v,pIdx,i); + } + sqlite3VdbeResolveLabel(v, endDistinctTest); + sqlite3DbFree(db, aGotoChng); + } + + /* + ** chng_addr_N: + ** regRowid = idx(rowid) // STAT4 only + ** stat_push(P, regChng, regRowid) // 3rd parameter STAT4 only + ** Next csr + ** if !eof(csr) goto next_row; + */ +#ifdef SQLITE_ENABLE_STAT4 + if( OptimizationEnabled(db, SQLITE_Stat4) ){ + assert( regRowid==(regStat+2) ); + if( HasRowid(pTab) ){ + sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, regRowid); + }else{ + Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable); + int j, k, regKey; + regKey = sqlite3GetTempRange(pParse, pPk->nKeyCol); + for(j=0; j<pPk->nKeyCol; j++){ + k = sqlite3TableColumnToIndex(pIdx, pPk->aiColumn[j]); + assert( k>=0 && k<pIdx->nColumn ); + sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, regKey+j); + analyzeVdbeCommentIndexWithColumnName(v,pIdx,k); + } + sqlite3VdbeAddOp3(v, OP_MakeRecord, regKey, pPk->nKeyCol, regRowid); + sqlite3ReleaseTempRange(pParse, regKey, pPk->nKeyCol); + } + } +#endif + assert( regChng==(regStat+1) ); + { + sqlite3VdbeAddFunctionCall(pParse, 1, regStat, regTemp, 2+IsStat4, + &statPushFuncdef, 0); + if( db->nAnalysisLimit ){ + int j1, j2, j3; + j1 = sqlite3VdbeAddOp1(v, OP_IsNull, regTemp); VdbeCoverage(v); + j2 = sqlite3VdbeAddOp1(v, OP_If, regTemp); VdbeCoverage(v); + j3 = sqlite3VdbeAddOp4Int(v, OP_SeekGT, iIdxCur, 0, regPrev, 1); + VdbeCoverage(v); + sqlite3VdbeJumpHere(v, j1); + sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, addrNextRow); VdbeCoverage(v); + sqlite3VdbeJumpHere(v, j2); + sqlite3VdbeJumpHere(v, j3); + }else{ + sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, addrNextRow); VdbeCoverage(v); + } + } + + /* Add the entry to the stat1 table. */ + callStatGet(pParse, regStat, STAT_GET_STAT1, regStat1); + assert( "BBB"[0]==SQLITE_AFF_TEXT ); + sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0); + sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid); + sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regTemp, regNewRowid); +#ifdef SQLITE_ENABLE_PREUPDATE_HOOK + sqlite3VdbeChangeP4(v, -1, (char*)pStat1, P4_TABLE); +#endif + sqlite3VdbeChangeP5(v, OPFLAG_APPEND); + + /* Add the entries to the stat4 table. */ +#ifdef SQLITE_ENABLE_STAT4 + if( OptimizationEnabled(db, SQLITE_Stat4) && db->nAnalysisLimit==0 ){ + int regEq = regStat1; + int regLt = regStat1+1; + int regDLt = regStat1+2; + int regSample = regStat1+3; + int regCol = regStat1+4; + int regSampleRowid = regCol + nCol; + int addrNext; + int addrIsNull; + u8 seekOp = HasRowid(pTab) ? OP_NotExists : OP_NotFound; + + if( doOnce ){ + int mxCol = nCol; + Index *pX; + + /* Compute the maximum number of columns in any index */ + for(pX=pTab->pIndex; pX; pX=pX->pNext){ + int nColX; /* Number of columns in pX */ + if( !HasRowid(pTab) && IsPrimaryKeyIndex(pX) ){ + nColX = pX->nKeyCol; + }else{ + nColX = pX->nColumn; + } + if( nColX>mxCol ) mxCol = nColX; + } + + /* Allocate space to compute results for the largest index */ + sqlite3TouchRegister(pParse, regCol+mxCol); + doOnce = 0; +#ifdef SQLITE_DEBUG + /* Verify that the call to sqlite3ClearTempRegCache() below + ** really is needed. + ** https://sqlite.org/forum/forumpost/83cb4a95a0 (2023-03-25) + */ + testcase( !sqlite3NoTempsInRange(pParse, regEq, regCol+mxCol) ); +#endif + sqlite3ClearTempRegCache(pParse); /* tag-20230325-1 */ + assert( sqlite3NoTempsInRange(pParse, regEq, regCol+mxCol) ); + } + assert( sqlite3NoTempsInRange(pParse, regEq, regCol+nCol) ); + + addrNext = sqlite3VdbeCurrentAddr(v); + callStatGet(pParse, regStat, STAT_GET_ROWID, regSampleRowid); + addrIsNull = sqlite3VdbeAddOp1(v, OP_IsNull, regSampleRowid); + VdbeCoverage(v); + callStatGet(pParse, regStat, STAT_GET_NEQ, regEq); + callStatGet(pParse, regStat, STAT_GET_NLT, regLt); + callStatGet(pParse, regStat, STAT_GET_NDLT, regDLt); + sqlite3VdbeAddOp4Int(v, seekOp, iTabCur, addrNext, regSampleRowid, 0); + VdbeCoverage(v); + for(i=0; i<nCol; i++){ + sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iTabCur, i, regCol+i); + } + sqlite3VdbeAddOp3(v, OP_MakeRecord, regCol, nCol, regSample); + sqlite3VdbeAddOp3(v, OP_MakeRecord, regTabname, 6, regTemp); + sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regNewRowid); + sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regTemp, regNewRowid); + sqlite3VdbeAddOp2(v, OP_Goto, 1, addrNext); /* P1==1 for end-of-loop */ + sqlite3VdbeJumpHere(v, addrIsNull); + } +#endif /* SQLITE_ENABLE_STAT4 */ + + /* End of analysis */ + sqlite3VdbeJumpHere(v, addrRewind); + } + + + /* Create a single sqlite_stat1 entry containing NULL as the index + ** name and the row count as the content. + */ + if( pOnlyIdx==0 && needTableCnt ){ + VdbeComment((v, "%s", pTab->zName)); + sqlite3VdbeAddOp2(v, OP_Count, iTabCur, regStat1); + jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1); VdbeCoverage(v); + sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname); + assert( "BBB"[0]==SQLITE_AFF_TEXT ); + sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp, "BBB", 0); + sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid); + sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regTemp, regNewRowid); + sqlite3VdbeChangeP5(v, OPFLAG_APPEND); +#ifdef SQLITE_ENABLE_PREUPDATE_HOOK + sqlite3VdbeChangeP4(v, -1, (char*)pStat1, P4_TABLE); +#endif + sqlite3VdbeJumpHere(v, jZeroRows); + } +} + + +/* +** Generate code that will cause the most recent index analysis to +** be loaded into internal hash tables where is can be used. +*/ +static void loadAnalysis(Parse *pParse, int iDb){ + Vdbe *v = sqlite3GetVdbe(pParse); + if( v ){ + sqlite3VdbeAddOp1(v, OP_LoadAnalysis, iDb); + } +} + +/* +** Generate code that will do an analysis of an entire database +*/ +static void analyzeDatabase(Parse *pParse, int iDb){ + sqlite3 *db = pParse->db; + Schema *pSchema = db->aDb[iDb].pSchema; /* Schema of database iDb */ + HashElem *k; + int iStatCur; + int iMem; + int iTab; + + sqlite3BeginWriteOperation(pParse, 0, iDb); + iStatCur = pParse->nTab; + pParse->nTab += 3; + openStatTable(pParse, iDb, iStatCur, 0, 0); + iMem = pParse->nMem+1; + iTab = pParse->nTab; + assert( sqlite3SchemaMutexHeld(db, iDb, 0) ); + for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){ + Table *pTab = (Table*)sqliteHashData(k); + analyzeOneTable(pParse, pTab, 0, iStatCur, iMem, iTab); +#ifdef SQLITE_ENABLE_STAT4 + iMem = sqlite3FirstAvailableRegister(pParse, iMem); +#else + assert( iMem==sqlite3FirstAvailableRegister(pParse,iMem) ); +#endif + } + loadAnalysis(pParse, iDb); +} + +/* +** Generate code that will do an analysis of a single table in +** a database. If pOnlyIdx is not NULL then it is a single index +** in pTab that should be analyzed. +*/ +static void analyzeTable(Parse *pParse, Table *pTab, Index *pOnlyIdx){ + int iDb; + int iStatCur; + + assert( pTab!=0 ); + assert( sqlite3BtreeHoldsAllMutexes(pParse->db) ); + iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema); + sqlite3BeginWriteOperation(pParse, 0, iDb); + iStatCur = pParse->nTab; + pParse->nTab += 3; + if( pOnlyIdx ){ + openStatTable(pParse, iDb, iStatCur, pOnlyIdx->zName, "idx"); + }else{ + openStatTable(pParse, iDb, iStatCur, pTab->zName, "tbl"); + } + analyzeOneTable(pParse, pTab, pOnlyIdx, iStatCur,pParse->nMem+1,pParse->nTab); + loadAnalysis(pParse, iDb); +} + +/* +** Generate code for the ANALYZE command. The parser calls this routine +** when it recognizes an ANALYZE command. +** +** ANALYZE -- 1 +** ANALYZE <database> -- 2 +** ANALYZE ?<database>.?<tablename> -- 3 +** +** Form 1 causes all indices in all attached databases to be analyzed. +** Form 2 analyzes all indices the single database named. +** Form 3 analyzes all indices associated with the named table. +*/ +void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){ + sqlite3 *db = pParse->db; + int iDb; + int i; + char *z, *zDb; + Table *pTab; + Index *pIdx; + Token *pTableName; + Vdbe *v; + + /* Read the database schema. If an error occurs, leave an error message + ** and code in pParse and return NULL. */ + assert( sqlite3BtreeHoldsAllMutexes(pParse->db) ); + if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){ + return; + } + + assert( pName2!=0 || pName1==0 ); + if( pName1==0 ){ + /* Form 1: Analyze everything */ + for(i=0; i<db->nDb; i++){ + if( i==1 ) continue; /* Do not analyze the TEMP database */ + analyzeDatabase(pParse, i); + } + }else if( pName2->n==0 && (iDb = sqlite3FindDb(db, pName1))>=0 ){ + /* Analyze the schema named as the argument */ + analyzeDatabase(pParse, iDb); + }else{ + /* Form 3: Analyze the table or index named as an argument */ + iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName); + if( iDb>=0 ){ + zDb = pName2->n ? db->aDb[iDb].zDbSName : 0; + z = sqlite3NameFromToken(db, pTableName); + if( z ){ + if( (pIdx = sqlite3FindIndex(db, z, zDb))!=0 ){ + analyzeTable(pParse, pIdx->pTable, pIdx); + }else if( (pTab = sqlite3LocateTable(pParse, 0, z, zDb))!=0 ){ + analyzeTable(pParse, pTab, 0); + } + sqlite3DbFree(db, z); + } + } + } + if( db->nSqlExec==0 && (v = sqlite3GetVdbe(pParse))!=0 ){ + sqlite3VdbeAddOp0(v, OP_Expire); + } +} + +/* +** Used to pass information from the analyzer reader through to the +** callback routine. +*/ +typedef struct analysisInfo analysisInfo; +struct analysisInfo { + sqlite3 *db; + const char *zDatabase; +}; + +/* +** The first argument points to a nul-terminated string containing a +** list of space separated integers. Read the first nOut of these into +** the array aOut[]. +*/ +static void decodeIntArray( + char *zIntArray, /* String containing int array to decode */ + int nOut, /* Number of slots in aOut[] */ + tRowcnt *aOut, /* Store integers here */ + LogEst *aLog, /* Or, if aOut==0, here */ + Index *pIndex /* Handle extra flags for this index, if not NULL */ +){ + char *z = zIntArray; + int c; + int i; + tRowcnt v; + +#ifdef SQLITE_ENABLE_STAT4 + if( z==0 ) z = ""; +#else + assert( z!=0 ); +#endif + for(i=0; *z && i<nOut; i++){ + v = 0; + while( (c=z[0])>='0' && c<='9' ){ + v = v*10 + c - '0'; + z++; + } +#ifdef SQLITE_ENABLE_STAT4 + if( aOut ) aOut[i] = v; + if( aLog ) aLog[i] = sqlite3LogEst(v); +#else + assert( aOut==0 ); + UNUSED_PARAMETER(aOut); + assert( aLog!=0 ); + aLog[i] = sqlite3LogEst(v); +#endif + if( *z==' ' ) z++; + } +#ifndef SQLITE_ENABLE_STAT4 + assert( pIndex!=0 ); { +#else + if( pIndex ){ +#endif + pIndex->bUnordered = 0; + pIndex->noSkipScan = 0; + while( z[0] ){ + if( sqlite3_strglob("unordered*", z)==0 ){ + pIndex->bUnordered = 1; + }else if( sqlite3_strglob("sz=[0-9]*", z)==0 ){ + int sz = sqlite3Atoi(z+3); + if( sz<2 ) sz = 2; + pIndex->szIdxRow = sqlite3LogEst(sz); + }else if( sqlite3_strglob("noskipscan*", z)==0 ){ + pIndex->noSkipScan = 1; + } +#ifdef SQLITE_ENABLE_COSTMULT + else if( sqlite3_strglob("costmult=[0-9]*",z)==0 ){ + pIndex->pTable->costMult = sqlite3LogEst(sqlite3Atoi(z+9)); + } +#endif + while( z[0]!=0 && z[0]!=' ' ) z++; + while( z[0]==' ' ) z++; + } + + /* Set the bLowQual flag if the peak number of rows obtained + ** from a full equality match is so large that a full table scan + ** seems likely to be faster than using the index. + */ + if( aLog[0] > 66 /* Index has more than 100 rows */ + && aLog[0] <= aLog[nOut-1] /* And only a single value seen */ + ){ + pIndex->bLowQual = 1; + } + } +} + +/* +** This callback is invoked once for each index when reading the +** sqlite_stat1 table. +** +** argv[0] = name of the table +** argv[1] = name of the index (might be NULL) +** argv[2] = results of analysis - on integer for each column +** +** Entries for which argv[1]==NULL simply record the number of rows in +** the table. +*/ +static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){ + analysisInfo *pInfo = (analysisInfo*)pData; + Index *pIndex; + Table *pTable; + const char *z; + + assert( argc==3 ); + UNUSED_PARAMETER2(NotUsed, argc); + + if( argv==0 || argv[0]==0 || argv[2]==0 ){ + return 0; + } + pTable = sqlite3FindTable(pInfo->db, argv[0], pInfo->zDatabase); + if( pTable==0 ){ + return 0; + } + if( argv[1]==0 ){ + pIndex = 0; + }else if( sqlite3_stricmp(argv[0],argv[1])==0 ){ + pIndex = sqlite3PrimaryKeyIndex(pTable); + }else{ + pIndex = sqlite3FindIndex(pInfo->db, argv[1], pInfo->zDatabase); + } + z = argv[2]; + + if( pIndex ){ + tRowcnt *aiRowEst = 0; + int nCol = pIndex->nKeyCol+1; +#ifdef SQLITE_ENABLE_STAT4 + /* Index.aiRowEst may already be set here if there are duplicate + ** sqlite_stat1 entries for this index. In that case just clobber + ** the old data with the new instead of allocating a new array. */ + if( pIndex->aiRowEst==0 ){ + pIndex->aiRowEst = (tRowcnt*)sqlite3MallocZero(sizeof(tRowcnt) * nCol); + if( pIndex->aiRowEst==0 ) sqlite3OomFault(pInfo->db); + } + aiRowEst = pIndex->aiRowEst; +#endif + pIndex->bUnordered = 0; + decodeIntArray((char*)z, nCol, aiRowEst, pIndex->aiRowLogEst, pIndex); + pIndex->hasStat1 = 1; + if( pIndex->pPartIdxWhere==0 ){ + pTable->nRowLogEst = pIndex->aiRowLogEst[0]; + pTable->tabFlags |= TF_HasStat1; + } + }else{ + Index fakeIdx; + fakeIdx.szIdxRow = pTable->szTabRow; +#ifdef SQLITE_ENABLE_COSTMULT + fakeIdx.pTable = pTable; +#endif + decodeIntArray((char*)z, 1, 0, &pTable->nRowLogEst, &fakeIdx); + pTable->szTabRow = fakeIdx.szIdxRow; + pTable->tabFlags |= TF_HasStat1; + } + + return 0; +} + +/* +** If the Index.aSample variable is not NULL, delete the aSample[] array +** and its contents. +*/ +void sqlite3DeleteIndexSamples(sqlite3 *db, Index *pIdx){ + assert( db!=0 ); + assert( pIdx!=0 ); +#ifdef SQLITE_ENABLE_STAT4 + if( pIdx->aSample ){ + int j; + for(j=0; j<pIdx->nSample; j++){ + IndexSample *p = &pIdx->aSample[j]; + sqlite3DbFree(db, p->p); + } + sqlite3DbFree(db, pIdx->aSample); + } + if( db->pnBytesFreed==0 ){ + pIdx->nSample = 0; + pIdx->aSample = 0; + } +#else + UNUSED_PARAMETER(db); + UNUSED_PARAMETER(pIdx); +#endif /* SQLITE_ENABLE_STAT4 */ +} + +#ifdef SQLITE_ENABLE_STAT4 +/* +** Populate the pIdx->aAvgEq[] array based on the samples currently +** stored in pIdx->aSample[]. +*/ +static void initAvgEq(Index *pIdx){ + if( pIdx ){ + IndexSample *aSample = pIdx->aSample; + IndexSample *pFinal = &aSample[pIdx->nSample-1]; + int iCol; + int nCol = 1; + if( pIdx->nSampleCol>1 ){ + /* If this is stat4 data, then calculate aAvgEq[] values for all + ** sample columns except the last. The last is always set to 1, as + ** once the trailing PK fields are considered all index keys are + ** unique. */ + nCol = pIdx->nSampleCol-1; + pIdx->aAvgEq[nCol] = 1; + } + for(iCol=0; iCol<nCol; iCol++){ + int nSample = pIdx->nSample; + int i; /* Used to iterate through samples */ + tRowcnt sumEq = 0; /* Sum of the nEq values */ + tRowcnt avgEq = 0; + tRowcnt nRow; /* Number of rows in index */ + i64 nSum100 = 0; /* Number of terms contributing to sumEq */ + i64 nDist100; /* Number of distinct values in index */ + + if( !pIdx->aiRowEst || iCol>=pIdx->nKeyCol || pIdx->aiRowEst[iCol+1]==0 ){ + nRow = pFinal->anLt[iCol]; + nDist100 = (i64)100 * pFinal->anDLt[iCol]; + nSample--; + }else{ + nRow = pIdx->aiRowEst[0]; + nDist100 = ((i64)100 * pIdx->aiRowEst[0]) / pIdx->aiRowEst[iCol+1]; + } + pIdx->nRowEst0 = nRow; + + /* Set nSum to the number of distinct (iCol+1) field prefixes that + ** occur in the stat4 table for this index. Set sumEq to the sum of + ** the nEq values for column iCol for the same set (adding the value + ** only once where there exist duplicate prefixes). */ + for(i=0; i<nSample; i++){ + if( i==(pIdx->nSample-1) + || aSample[i].anDLt[iCol]!=aSample[i+1].anDLt[iCol] + ){ + sumEq += aSample[i].anEq[iCol]; + nSum100 += 100; + } + } + + if( nDist100>nSum100 && sumEq<nRow ){ + avgEq = ((i64)100 * (nRow - sumEq))/(nDist100 - nSum100); + } + if( avgEq==0 ) avgEq = 1; + pIdx->aAvgEq[iCol] = avgEq; + } + } +} + +/* +** Look up an index by name. Or, if the name of a WITHOUT ROWID table +** is supplied instead, find the PRIMARY KEY index for that table. +*/ +static Index *findIndexOrPrimaryKey( + sqlite3 *db, + const char *zName, + const char *zDb +){ + Index *pIdx = sqlite3FindIndex(db, zName, zDb); + if( pIdx==0 ){ + Table *pTab = sqlite3FindTable(db, zName, zDb); + if( pTab && !HasRowid(pTab) ) pIdx = sqlite3PrimaryKeyIndex(pTab); + } + return pIdx; +} + +/* +** Load the content from either the sqlite_stat4 +** into the relevant Index.aSample[] arrays. +** +** Arguments zSql1 and zSql2 must point to SQL statements that return +** data equivalent to the following: +** +** zSql1: SELECT idx,count(*) FROM %Q.sqlite_stat4 GROUP BY idx +** zSql2: SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat4 +** +** where %Q is replaced with the database name before the SQL is executed. +*/ +static int loadStatTbl( + sqlite3 *db, /* Database handle */ + const char *zSql1, /* SQL statement 1 (see above) */ + const char *zSql2, /* SQL statement 2 (see above) */ + const char *zDb /* Database name (e.g. "main") */ +){ + int rc; /* Result codes from subroutines */ + sqlite3_stmt *pStmt = 0; /* An SQL statement being run */ + char *zSql; /* Text of the SQL statement */ + Index *pPrevIdx = 0; /* Previous index in the loop */ + IndexSample *pSample; /* A slot in pIdx->aSample[] */ + + assert( db->lookaside.bDisable ); + zSql = sqlite3MPrintf(db, zSql1, zDb); + if( !zSql ){ + return SQLITE_NOMEM_BKPT; + } + rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0); + sqlite3DbFree(db, zSql); + if( rc ) return rc; + + while( sqlite3_step(pStmt)==SQLITE_ROW ){ + int nIdxCol = 1; /* Number of columns in stat4 records */ + + char *zIndex; /* Index name */ + Index *pIdx; /* Pointer to the index object */ + int nSample; /* Number of samples */ + int nByte; /* Bytes of space required */ + int i; /* Bytes of space required */ + tRowcnt *pSpace; + + zIndex = (char *)sqlite3_column_text(pStmt, 0); + if( zIndex==0 ) continue; + nSample = sqlite3_column_int(pStmt, 1); + pIdx = findIndexOrPrimaryKey(db, zIndex, zDb); + assert( pIdx==0 || pIdx->nSample==0 ); + if( pIdx==0 ) continue; + if( pIdx->aSample!=0 ){ + /* The same index appears in sqlite_stat4 under multiple names */ + continue; + } + assert( !HasRowid(pIdx->pTable) || pIdx->nColumn==pIdx->nKeyCol+1 ); + if( !HasRowid(pIdx->pTable) && IsPrimaryKeyIndex(pIdx) ){ + nIdxCol = pIdx->nKeyCol; + }else{ + nIdxCol = pIdx->nColumn; + } + pIdx->nSampleCol = nIdxCol; + pIdx->mxSample = nSample; + nByte = sizeof(IndexSample) * nSample; + nByte += sizeof(tRowcnt) * nIdxCol * 3 * nSample; + nByte += nIdxCol * sizeof(tRowcnt); /* Space for Index.aAvgEq[] */ + + pIdx->aSample = sqlite3DbMallocZero(db, nByte); + if( pIdx->aSample==0 ){ + sqlite3_finalize(pStmt); + return SQLITE_NOMEM_BKPT; + } + pSpace = (tRowcnt*)&pIdx->aSample[nSample]; + pIdx->aAvgEq = pSpace; pSpace += nIdxCol; + pIdx->pTable->tabFlags |= TF_HasStat4; + for(i=0; i<nSample; i++){ + pIdx->aSample[i].anEq = pSpace; pSpace += nIdxCol; + pIdx->aSample[i].anLt = pSpace; pSpace += nIdxCol; + pIdx->aSample[i].anDLt = pSpace; pSpace += nIdxCol; + } + assert( ((u8*)pSpace)-nByte==(u8*)(pIdx->aSample) ); + } + rc = sqlite3_finalize(pStmt); + if( rc ) return rc; + + zSql = sqlite3MPrintf(db, zSql2, zDb); + if( !zSql ){ + return SQLITE_NOMEM_BKPT; + } + rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0); + sqlite3DbFree(db, zSql); + if( rc ) return rc; + + while( sqlite3_step(pStmt)==SQLITE_ROW ){ + char *zIndex; /* Index name */ + Index *pIdx; /* Pointer to the index object */ + int nCol = 1; /* Number of columns in index */ + + zIndex = (char *)sqlite3_column_text(pStmt, 0); + if( zIndex==0 ) continue; + pIdx = findIndexOrPrimaryKey(db, zIndex, zDb); + if( pIdx==0 ) continue; + if( pIdx->nSample>=pIdx->mxSample ){ + /* Too many slots used because the same index appears in + ** sqlite_stat4 using multiple names */ + continue; + } + /* This next condition is true if data has already been loaded from + ** the sqlite_stat4 table. */ + nCol = pIdx->nSampleCol; + if( pIdx!=pPrevIdx ){ + initAvgEq(pPrevIdx); + pPrevIdx = pIdx; + } + pSample = &pIdx->aSample[pIdx->nSample]; + decodeIntArray((char*)sqlite3_column_text(pStmt,1),nCol,pSample->anEq,0,0); + decodeIntArray((char*)sqlite3_column_text(pStmt,2),nCol,pSample->anLt,0,0); + decodeIntArray((char*)sqlite3_column_text(pStmt,3),nCol,pSample->anDLt,0,0); + + /* Take a copy of the sample. Add 8 extra 0x00 bytes the end of the buffer. + ** This is in case the sample record is corrupted. In that case, the + ** sqlite3VdbeRecordCompare() may read up to two varints past the + ** end of the allocated buffer before it realizes it is dealing with + ** a corrupt record. Or it might try to read a large integer from the + ** buffer. In any case, eight 0x00 bytes prevents this from causing + ** a buffer overread. */ + pSample->n = sqlite3_column_bytes(pStmt, 4); + pSample->p = sqlite3DbMallocZero(db, pSample->n + 8); + if( pSample->p==0 ){ + sqlite3_finalize(pStmt); + return SQLITE_NOMEM_BKPT; + } + if( pSample->n ){ + memcpy(pSample->p, sqlite3_column_blob(pStmt, 4), pSample->n); + } + pIdx->nSample++; + } + rc = sqlite3_finalize(pStmt); + if( rc==SQLITE_OK ) initAvgEq(pPrevIdx); + return rc; +} + +/* +** Load content from the sqlite_stat4 table into +** the Index.aSample[] arrays of all indices. +*/ +static int loadStat4(sqlite3 *db, const char *zDb){ + int rc = SQLITE_OK; /* Result codes from subroutines */ + const Table *pStat4; + + assert( db->lookaside.bDisable ); + if( OptimizationEnabled(db, SQLITE_Stat4) + && (pStat4 = sqlite3FindTable(db, "sqlite_stat4", zDb))!=0 + && IsOrdinaryTable(pStat4) + ){ + rc = loadStatTbl(db, + "SELECT idx,count(*) FROM %Q.sqlite_stat4 GROUP BY idx COLLATE nocase", + "SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat4", + zDb + ); + } + return rc; +} +#endif /* SQLITE_ENABLE_STAT4 */ + +/* +** Load the content of the sqlite_stat1 and sqlite_stat4 tables. The +** contents of sqlite_stat1 are used to populate the Index.aiRowEst[] +** arrays. The contents of sqlite_stat4 are used to populate the +** Index.aSample[] arrays. +** +** If the sqlite_stat1 table is not present in the database, SQLITE_ERROR +** is returned. In this case, even if SQLITE_ENABLE_STAT4 was defined +** during compilation and the sqlite_stat4 table is present, no data is +** read from it. +** +** If SQLITE_ENABLE_STAT4 was defined during compilation and the +** sqlite_stat4 table is not present in the database, SQLITE_ERROR is +** returned. However, in this case, data is read from the sqlite_stat1 +** table (if it is present) before returning. +** +** If an OOM error occurs, this function always sets db->mallocFailed. +** This means if the caller does not care about other errors, the return +** code may be ignored. +*/ +int sqlite3AnalysisLoad(sqlite3 *db, int iDb){ + analysisInfo sInfo; + HashElem *i; + char *zSql; + int rc = SQLITE_OK; + Schema *pSchema = db->aDb[iDb].pSchema; + const Table *pStat1; + + assert( iDb>=0 && iDb<db->nDb ); + assert( db->aDb[iDb].pBt!=0 ); + + /* Clear any prior statistics */ + assert( sqlite3SchemaMutexHeld(db, iDb, 0) ); + for(i=sqliteHashFirst(&pSchema->tblHash); i; i=sqliteHashNext(i)){ + Table *pTab = sqliteHashData(i); + pTab->tabFlags &= ~TF_HasStat1; + } + for(i=sqliteHashFirst(&pSchema->idxHash); i; i=sqliteHashNext(i)){ + Index *pIdx = sqliteHashData(i); + pIdx->hasStat1 = 0; +#ifdef SQLITE_ENABLE_STAT4 + sqlite3DeleteIndexSamples(db, pIdx); + pIdx->aSample = 0; +#endif + } + + /* Load new statistics out of the sqlite_stat1 table */ + sInfo.db = db; + sInfo.zDatabase = db->aDb[iDb].zDbSName; + if( (pStat1 = sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)) + && IsOrdinaryTable(pStat1) + ){ + zSql = sqlite3MPrintf(db, + "SELECT tbl,idx,stat FROM %Q.sqlite_stat1", sInfo.zDatabase); + if( zSql==0 ){ + rc = SQLITE_NOMEM_BKPT; + }else{ + rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0); + sqlite3DbFree(db, zSql); + } + } + + /* Set appropriate defaults on all indexes not in the sqlite_stat1 table */ + assert( sqlite3SchemaMutexHeld(db, iDb, 0) ); + for(i=sqliteHashFirst(&pSchema->idxHash); i; i=sqliteHashNext(i)){ + Index *pIdx = sqliteHashData(i); + if( !pIdx->hasStat1 ) sqlite3DefaultRowEst(pIdx); + } + + /* Load the statistics from the sqlite_stat4 table. */ +#ifdef SQLITE_ENABLE_STAT4 + if( rc==SQLITE_OK ){ + DisableLookaside; + rc = loadStat4(db, sInfo.zDatabase); + EnableLookaside; + } + for(i=sqliteHashFirst(&pSchema->idxHash); i; i=sqliteHashNext(i)){ + Index *pIdx = sqliteHashData(i); + sqlite3_free(pIdx->aiRowEst); + pIdx->aiRowEst = 0; + } +#endif + + if( rc==SQLITE_NOMEM ){ + sqlite3OomFault(db); + } + return rc; +} + + +#endif /* SQLITE_OMIT_ANALYZE */ |