/* ** 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 ** The sqlite_stat2 table is superseded by sqlite_stat3, which is only ** created and used by SQLite versions 3.7.9 through 3.29.0 when ** SQLITE_ENABLE_STAT3 defined.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; izDbSName))==0 ){ if( iregRoot. 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; inRowid ){ 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; inCol; i++) sampleClear(p->db, p->aBest+i); for(i=0; imxSample; 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; iaBest[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; ianEq[i]>pOld->anEq[i] ) return 1; if( pNew->anEq[i]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->iColiCol ) 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; imxSample; 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->nSamplemxSample || 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; jnCol; j++) assert( p->a[i].anEq[j]>0 ); } /* Update the anEq[] fields of any samples already collected. */ if( iChngnMaxEqZero ){ for(i=p->nSample-1; i>=0; i--){ int j; for(j=iChng; jnCol; 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( iChngnCol ); if( p->nRow==0 ){ /* This is the first call to this function. Do initialization. */ #ifdef SQLITE_ENABLE_STAT4 for(i=0; inCol; 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; icurrent.anEq[i]++; } #endif for(i=iChng; inCol; 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; inKeyCol; 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->iGetnSample ){ 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->iGetnSample ); 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; inCol; 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 && knColumn ); 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; iazColl[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; ipTable); int j, k, regKey; regKey = sqlite3GetTempRange(pParse, pPk->nKeyCol); for(j=0; jnKeyCol; j++){ k = sqlite3TableColumnToIndex(pIdx, pPk->aiColumn[j]); assert( k>=0 && knColumn ); 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; izName)); 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 -- 2 ** ANALYZE ?.? -- 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; inDb; 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='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; jnSample; 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; iColnSample; 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; inSample-1) || aSample[i].anDLt[iCol]!=aSample[i+1].anDLt[iCol] ){ sumEq += aSample[i].anEq[iCol]; nSum100 += 100; } } if( nDist100>nSum100 && sumEqaAvgEq[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; iaSample[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 && iDbnDb ); 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 */