f78ceafdce
used new shared cache functionality (yay) --HG-- extra : convert_revision : svn%3A39bc706e-5318-0410-9160-8a85361fbb7c/trunk%401651
263 lines
8.6 KiB
C
263 lines
8.6 KiB
C
/*
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** 2003 April 6
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This file contains code used to implement the VACUUM command.
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**
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** Most of the code in this file may be omitted by defining the
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** SQLITE_OMIT_VACUUM macro.
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**
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** $Id$
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*/
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#include "sqliteInt.h"
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#include "vdbeInt.h"
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#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
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/*
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** Execute zSql on database db. Return an error code.
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*/
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static int execSql(sqlite3 *db, const char *zSql){
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sqlite3_stmt *pStmt;
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if( !zSql ){
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return SQLITE_NOMEM;
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}
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if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
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return sqlite3_errcode(db);
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}
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while( SQLITE_ROW==sqlite3_step(pStmt) ){}
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return sqlite3_finalize(pStmt);
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}
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/*
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** Execute zSql on database db. The statement returns exactly
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** one column. Execute this as SQL on the same database.
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*/
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static int execExecSql(sqlite3 *db, const char *zSql){
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sqlite3_stmt *pStmt;
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int rc;
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rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
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if( rc!=SQLITE_OK ) return rc;
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while( SQLITE_ROW==sqlite3_step(pStmt) ){
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rc = execSql(db, (char*)sqlite3_column_text(pStmt, 0));
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if( rc!=SQLITE_OK ){
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sqlite3_finalize(pStmt);
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return rc;
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}
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}
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return sqlite3_finalize(pStmt);
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}
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/*
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** The non-standard VACUUM command is used to clean up the database,
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** collapse free space, etc. It is modelled after the VACUUM command
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** in PostgreSQL.
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**
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** In version 1.0.x of SQLite, the VACUUM command would call
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** gdbm_reorganize() on all the database tables. But beginning
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** with 2.0.0, SQLite no longer uses GDBM so this command has
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** become a no-op.
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*/
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void sqlite3Vacuum(Parse *pParse){
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Vdbe *v = sqlite3GetVdbe(pParse);
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if( v ){
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sqlite3VdbeAddOp(v, OP_Vacuum, 0, 0);
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}
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return;
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}
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/*
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** This routine implements the OP_Vacuum opcode of the VDBE.
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*/
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int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
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int rc = SQLITE_OK; /* Return code from service routines */
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Btree *pMain; /* The database being vacuumed */
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Btree *pTemp; /* The temporary database we vacuum into */
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char *zSql = 0; /* SQL statements */
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int saved_flags; /* Saved value of the db->flags */
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Db *pDb = 0; /* Database to detach at end of vacuum */
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/* Save the current value of the write-schema flag before setting it. */
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saved_flags = db->flags;
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db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks;
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if( !db->autoCommit ){
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sqlite3SetString(pzErrMsg, "cannot VACUUM from within a transaction",
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(char*)0);
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rc = SQLITE_ERROR;
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goto end_of_vacuum;
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}
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pMain = db->aDb[0].pBt;
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/* Attach the temporary database as 'vacuum_db'. The synchronous pragma
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** can be set to 'off' for this file, as it is not recovered if a crash
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** occurs anyway. The integrity of the database is maintained by a
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** (possibly synchronous) transaction opened on the main database before
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** sqlite3BtreeCopyFile() is called.
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**
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** An optimisation would be to use a non-journaled pager.
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*/
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zSql = "ATTACH '' AS vacuum_db;";
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rc = execSql(db, zSql);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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pDb = &db->aDb[db->nDb-1];
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assert( strcmp(db->aDb[db->nDb-1].zName,"vacuum_db")==0 );
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pTemp = db->aDb[db->nDb-1].pBt;
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sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain),
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sqlite3BtreeGetReserve(pMain));
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if( db->mallocFailed ){
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rc = SQLITE_NOMEM;
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goto end_of_vacuum;
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}
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assert( sqlite3BtreeGetPageSize(pTemp)==sqlite3BtreeGetPageSize(pMain) );
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rc = execSql(db, "PRAGMA vacuum_db.synchronous=OFF");
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if( rc!=SQLITE_OK ){
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goto end_of_vacuum;
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}
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#ifndef SQLITE_OMIT_AUTOVACUUM
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sqlite3BtreeSetAutoVacuum(pTemp, sqlite3BtreeGetAutoVacuum(pMain));
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#endif
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/* Begin a transaction */
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rc = execSql(db, "BEGIN EXCLUSIVE;");
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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/* Query the schema of the main database. Create a mirror schema
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** in the temporary database.
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*/
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rc = execExecSql(db,
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"SELECT 'CREATE TABLE vacuum_db.' || substr(sql,14,100000000) "
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" FROM sqlite_master WHERE type='table' AND name!='sqlite_sequence'"
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" AND rootpage>0"
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);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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rc = execExecSql(db,
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"SELECT 'CREATE INDEX vacuum_db.' || substr(sql,14,100000000)"
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" FROM sqlite_master WHERE sql LIKE 'CREATE INDEX %' ");
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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rc = execExecSql(db,
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"SELECT 'CREATE UNIQUE INDEX vacuum_db.' || substr(sql,21,100000000) "
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" FROM sqlite_master WHERE sql LIKE 'CREATE UNIQUE INDEX %'");
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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/* Loop through the tables in the main database. For each, do
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** an "INSERT INTO vacuum_db.xxx SELECT * FROM xxx;" to copy
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** the contents to the temporary database.
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*/
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rc = execExecSql(db,
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"SELECT 'INSERT INTO vacuum_db.' || quote(name) "
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"|| ' SELECT * FROM ' || quote(name) || ';'"
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"FROM sqlite_master "
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"WHERE type = 'table' AND name!='sqlite_sequence' "
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" AND rootpage>0"
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);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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/* Copy over the sequence table
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*/
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rc = execExecSql(db,
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"SELECT 'DELETE FROM vacuum_db.' || quote(name) || ';' "
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"FROM vacuum_db.sqlite_master WHERE name='sqlite_sequence' "
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);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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rc = execExecSql(db,
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"SELECT 'INSERT INTO vacuum_db.' || quote(name) "
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"|| ' SELECT * FROM ' || quote(name) || ';' "
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"FROM vacuum_db.sqlite_master WHERE name=='sqlite_sequence';"
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);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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/* Copy the triggers, views, and virtual tables from the main database
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** over to the temporary database. None of these objects has any
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** associated storage, so all we have to do is copy their entries
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** from the SQLITE_MASTER table.
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*/
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rc = execSql(db,
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"INSERT INTO vacuum_db.sqlite_master "
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" SELECT type, name, tbl_name, rootpage, sql"
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" FROM sqlite_master"
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" WHERE type='view' OR type='trigger'"
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" OR (type='table' AND rootpage=0)"
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);
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if( rc ) goto end_of_vacuum;
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/* At this point, unless the main db was completely empty, there is now a
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** transaction open on the vacuum database, but not on the main database.
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** Open a btree level transaction on the main database. This allows a
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** call to sqlite3BtreeCopyFile(). The main database btree level
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** transaction is then committed, so the SQL level never knows it was
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** opened for writing. This way, the SQL transaction used to create the
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** temporary database never needs to be committed.
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*/
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if( rc==SQLITE_OK ){
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u32 meta;
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int i;
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/* This array determines which meta meta values are preserved in the
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** vacuum. Even entries are the meta value number and odd entries
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** are an increment to apply to the meta value after the vacuum.
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** The increment is used to increase the schema cookie so that other
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** connections to the same database will know to reread the schema.
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*/
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static const unsigned char aCopy[] = {
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1, 1, /* Add one to the old schema cookie */
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3, 0, /* Preserve the default page cache size */
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5, 0, /* Preserve the default text encoding */
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6, 0, /* Preserve the user version */
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};
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assert( 1==sqlite3BtreeIsInTrans(pTemp) );
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assert( 1==sqlite3BtreeIsInTrans(pMain) );
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/* Copy Btree meta values */
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for(i=0; i<sizeof(aCopy)/sizeof(aCopy[0]); i+=2){
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rc = sqlite3BtreeGetMeta(pMain, aCopy[i], &meta);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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rc = sqlite3BtreeUpdateMeta(pTemp, aCopy[i], meta+aCopy[i+1]);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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}
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rc = sqlite3BtreeCopyFile(pMain, pTemp);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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rc = sqlite3BtreeCommit(pTemp);
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if( rc!=SQLITE_OK ) goto end_of_vacuum;
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rc = sqlite3BtreeCommit(pMain);
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}
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end_of_vacuum:
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/* Restore the original value of db->flags */
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db->flags = saved_flags;
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/* Currently there is an SQL level transaction open on the vacuum
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** database. No locks are held on any other files (since the main file
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** was committed at the btree level). So it safe to end the transaction
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** by manually setting the autoCommit flag to true and detaching the
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** vacuum database. The vacuum_db journal file is deleted when the pager
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** is closed by the DETACH.
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*/
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db->autoCommit = 1;
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if( pDb ){
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sqlite3BtreeClose(pDb->pBt);
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pDb->pBt = 0;
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pDb->pSchema = 0;
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}
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sqlite3ResetInternalSchema(db, 0);
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return rc;
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}
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#endif /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */
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