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| -rw-r--r-- | ext/expert/sqlite3expert.h | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/ext/expert/sqlite3expert.h b/ext/expert/sqlite3expert.h new file mode 100644 index 0000000..6048137 --- /dev/null +++ b/ext/expert/sqlite3expert.h @@ -0,0 +1,168 @@ +/* +** 2017 April 07 +** +** 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. +** +************************************************************************* +*/ +#if !defined(SQLITEEXPERT_H) +#define SQLITEEXPERT_H 1 +#include "sqlite3.h" + +typedef struct sqlite3expert sqlite3expert; + +/* +** Create a new sqlite3expert object. +** +** If successful, a pointer to the new object is returned and (*pzErr) set +** to NULL. Or, if an error occurs, NULL is returned and (*pzErr) set to +** an English-language error message. In this case it is the responsibility +** of the caller to eventually free the error message buffer using +** sqlite3_free(). +*/ +sqlite3expert *sqlite3_expert_new(sqlite3 *db, char **pzErr); + +/* +** Configure an sqlite3expert object. +** +** EXPERT_CONFIG_SAMPLE: +** By default, sqlite3_expert_analyze() generates sqlite_stat1 data for +** each candidate index. This involves scanning and sorting the entire +** contents of each user database table once for each candidate index +** associated with the table. For large databases, this can be +** prohibitively slow. This option allows the sqlite3expert object to +** be configured so that sqlite_stat1 data is instead generated based on a +** subset of each table, or so that no sqlite_stat1 data is used at all. +** +** A single integer argument is passed to this option. If the value is less +** than or equal to zero, then no sqlite_stat1 data is generated or used by +** the analysis - indexes are recommended based on the database schema only. +** Or, if the value is 100 or greater, complete sqlite_stat1 data is +** generated for each candidate index (this is the default). Finally, if the +** value falls between 0 and 100, then it represents the percentage of user +** table rows that should be considered when generating sqlite_stat1 data. +** +** Examples: +** +** // Do not generate any sqlite_stat1 data +** sqlite3_expert_config(pExpert, EXPERT_CONFIG_SAMPLE, 0); +** +** // Generate sqlite_stat1 data based on 10% of the rows in each table. +** sqlite3_expert_config(pExpert, EXPERT_CONFIG_SAMPLE, 10); +*/ +int sqlite3_expert_config(sqlite3expert *p, int op, ...); + +#define EXPERT_CONFIG_SAMPLE 1 /* int */ + +/* +** Specify zero or more SQL statements to be included in the analysis. +** +** Buffer zSql must contain zero or more complete SQL statements. This +** function parses all statements contained in the buffer and adds them +** to the internal list of statements to analyze. If successful, SQLITE_OK +** is returned and (*pzErr) set to NULL. Or, if an error occurs - for example +** due to a error in the SQL - an SQLite error code is returned and (*pzErr) +** may be set to point to an English language error message. In this case +** the caller is responsible for eventually freeing the error message buffer +** using sqlite3_free(). +** +** If an error does occur while processing one of the statements in the +** buffer passed as the second argument, none of the statements in the +** buffer are added to the analysis. +** +** This function must be called before sqlite3_expert_analyze(). If a call +** to this function is made on an sqlite3expert object that has already +** been passed to sqlite3_expert_analyze() SQLITE_MISUSE is returned +** immediately and no statements are added to the analysis. +*/ +int sqlite3_expert_sql( + sqlite3expert *p, /* From a successful sqlite3_expert_new() */ + const char *zSql, /* SQL statement(s) to add */ + char **pzErr /* OUT: Error message (if any) */ +); + + +/* +** This function is called after the sqlite3expert object has been configured +** with all SQL statements using sqlite3_expert_sql() to actually perform +** the analysis. Once this function has been called, it is not possible to +** add further SQL statements to the analysis. +** +** If successful, SQLITE_OK is returned and (*pzErr) is set to NULL. Or, if +** an error occurs, an SQLite error code is returned and (*pzErr) set to +** point to a buffer containing an English language error message. In this +** case it is the responsibility of the caller to eventually free the buffer +** using sqlite3_free(). +** +** If an error does occur within this function, the sqlite3expert object +** is no longer useful for any purpose. At that point it is no longer +** possible to add further SQL statements to the object or to re-attempt +** the analysis. The sqlite3expert object must still be freed using a call +** sqlite3_expert_destroy(). +*/ +int sqlite3_expert_analyze(sqlite3expert *p, char **pzErr); + +/* +** Return the total number of statements loaded using sqlite3_expert_sql(). +** The total number of SQL statements may be different from the total number +** to calls to sqlite3_expert_sql(). +*/ +int sqlite3_expert_count(sqlite3expert*); + +/* +** Return a component of the report. +** +** This function is called after sqlite3_expert_analyze() to extract the +** results of the analysis. Each call to this function returns either a +** NULL pointer or a pointer to a buffer containing a nul-terminated string. +** The value passed as the third argument must be one of the EXPERT_REPORT_* +** #define constants defined below. +** +** For some EXPERT_REPORT_* parameters, the buffer returned contains +** information relating to a specific SQL statement. In these cases that +** SQL statement is identified by the value passed as the second argument. +** SQL statements are numbered from 0 in the order in which they are parsed. +** If an out-of-range value (less than zero or equal to or greater than the +** value returned by sqlite3_expert_count()) is passed as the second argument +** along with such an EXPERT_REPORT_* parameter, NULL is always returned. +** +** EXPERT_REPORT_SQL: +** Return the text of SQL statement iStmt. +** +** EXPERT_REPORT_INDEXES: +** Return a buffer containing the CREATE INDEX statements for all recommended +** indexes for statement iStmt. If there are no new recommeded indexes, NULL +** is returned. +** +** EXPERT_REPORT_PLAN: +** Return a buffer containing the EXPLAIN QUERY PLAN output for SQL query +** iStmt after the proposed indexes have been added to the database schema. +** +** EXPERT_REPORT_CANDIDATES: +** Return a pointer to a buffer containing the CREATE INDEX statements +** for all indexes that were tested (for all SQL statements). The iStmt +** parameter is ignored for EXPERT_REPORT_CANDIDATES calls. +*/ +const char *sqlite3_expert_report(sqlite3expert*, int iStmt, int eReport); + +/* +** Values for the third argument passed to sqlite3_expert_report(). +*/ +#define EXPERT_REPORT_SQL 1 +#define EXPERT_REPORT_INDEXES 2 +#define EXPERT_REPORT_PLAN 3 +#define EXPERT_REPORT_CANDIDATES 4 + +/* +** Free an (sqlite3expert*) handle and all associated resources. There +** should be one call to this function for each successful call to +** sqlite3-expert_new(). +*/ +void sqlite3_expert_destroy(sqlite3expert*); + +#endif /* !defined(SQLITEEXPERT_H) */ |