--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/engine/sqlite/src/vacuum.cpp Thu Feb 25 14:29:19 2010 +0000
@@ -0,0 +1,263 @@
+/*
+** 2003 April 6
+**
+** 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 used to implement the VACUUM command.
+**
+** Most of the code in this file may be omitted by defining the
+** SQLITE_OMIT_VACUUM macro.
+**
+** $Id: vacuum.cpp 1282 2008-11-13 09:31:33Z LarsPson $
+*/
+#include "sqliteInt.h"
+#include "vdbeInt.h"
+
+#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
+/*
+** Execute zSql on database db. Return an error code.
+*/
+static int execSql(sqlite3 *db, const char *zSql){
+ sqlite3_stmt *pStmt;
+ if( !zSql ){
+ return SQLITE_NOMEM;
+ }
+ if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
+ return sqlite3_errcode(db);
+ }
+ while( SQLITE_ROW==sqlite3_step(pStmt) ){}
+ return sqlite3_finalize(pStmt);
+}
+
+/*
+** Execute zSql on database db. The statement returns exactly
+** one column. Execute this as SQL on the same database.
+*/
+static int execExecSql(sqlite3 *db, const char *zSql){
+ sqlite3_stmt *pStmt;
+ int rc;
+
+ rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+ if( rc!=SQLITE_OK ) return rc;
+
+ while( SQLITE_ROW==sqlite3_step(pStmt) ){
+ rc = execSql(db, (char*)sqlite3_column_text(pStmt, 0));
+ if( rc!=SQLITE_OK ){
+ sqlite3_finalize(pStmt);
+ return rc;
+ }
+ }
+
+ return sqlite3_finalize(pStmt);
+}
+
+/*
+** The non-standard VACUUM command is used to clean up the database,
+** collapse free space, etc. It is modelled after the VACUUM command
+** in PostgreSQL.
+**
+** In version 1.0.x of SQLite, the VACUUM command would call
+** gdbm_reorganize() on all the database tables. But beginning
+** with 2.0.0, SQLite no longer uses GDBM so this command has
+** become a no-op.
+*/
+void sqlite3Vacuum(Parse *pParse){
+ Vdbe *v = sqlite3GetVdbe(pParse);
+ if( v ){
+ sqlite3VdbeAddOp(v, OP_Vacuum, 0, 0);
+ }
+ return;
+}
+
+/*
+** This routine implements the OP_Vacuum opcode of the VDBE.
+*/
+int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
+ int rc = SQLITE_OK; /* Return code from service routines */
+ Btree *pMain; /* The database being vacuumed */
+ Btree *pTemp; /* The temporary database we vacuum into */
+ char *zSql = 0; /* SQL statements */
+ int saved_flags; /* Saved value of the db->flags */
+ Db *pDb = 0; /* Database to detach at end of vacuum */
+
+ /* Save the current value of the write-schema flag before setting it. */
+ saved_flags = db->flags;
+ db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks;
+
+ if( !db->autoCommit ){
+ sqlite3SetString(pzErrMsg, "cannot VACUUM from within a transaction",
+ (char*)0);
+ rc = SQLITE_ERROR;
+ goto end_of_vacuum;
+ }
+ pMain = db->aDb[0].pBt;
+
+ /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
+ ** can be set to 'off' for this file, as it is not recovered if a crash
+ ** occurs anyway. The integrity of the database is maintained by a
+ ** (possibly synchronous) transaction opened on the main database before
+ ** sqlite3BtreeCopyFile() is called.
+ **
+ ** An optimisation would be to use a non-journaled pager.
+ */
+ zSql = "ATTACH '' AS vacuum_db;";
+ rc = execSql(db, zSql);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ pDb = &db->aDb[db->nDb-1];
+ assert( strcmp(db->aDb[db->nDb-1].zName,"vacuum_db")==0 );
+ pTemp = db->aDb[db->nDb-1].pBt;
+ sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain),
+ sqlite3BtreeGetReserve(pMain));
+ if( db->mallocFailed ){
+ rc = SQLITE_NOMEM;
+ goto end_of_vacuum;
+ }
+ assert( sqlite3BtreeGetPageSize(pTemp)==sqlite3BtreeGetPageSize(pMain) );
+ rc = execSql(db, "PRAGMA vacuum_db.synchronous=OFF");
+ if( rc!=SQLITE_OK ){
+ goto end_of_vacuum;
+ }
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ sqlite3BtreeSetAutoVacuum(pTemp, db->nextAutovac>=0 ? db->nextAutovac :
+ sqlite3BtreeGetAutoVacuum(pMain));
+#endif
+
+ /* Begin a transaction */
+ rc = execSql(db, "BEGIN EXCLUSIVE;");
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+ /* Query the schema of the main database. Create a mirror schema
+ ** in the temporary database.
+ */
+ rc = execExecSql(db,
+ "SELECT 'CREATE TABLE vacuum_db.' || substr(sql,14) "
+ " FROM sqlite_master WHERE type='table' AND name!='sqlite_sequence'"
+ " AND rootpage>0"
+ );
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = execExecSql(db,
+ "SELECT 'CREATE INDEX vacuum_db.' || substr(sql,14)"
+ " FROM sqlite_master WHERE sql LIKE 'CREATE INDEX %' ");
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = execExecSql(db,
+ "SELECT 'CREATE UNIQUE INDEX vacuum_db.' || substr(sql,21) "
+ " FROM sqlite_master WHERE sql LIKE 'CREATE UNIQUE INDEX %'");
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+ /* Loop through the tables in the main database. For each, do
+ ** an "INSERT INTO vacuum_db.xxx SELECT * FROM xxx;" to copy
+ ** the contents to the temporary database.
+ */
+ rc = execExecSql(db,
+ "SELECT 'INSERT INTO vacuum_db.' || quote(name) "
+ "|| ' SELECT * FROM ' || quote(name) || ';'"
+ "FROM sqlite_master "
+ "WHERE type = 'table' AND name!='sqlite_sequence' "
+ " AND rootpage>0"
+
+ );
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+ /* Copy over the sequence table
+ */
+ rc = execExecSql(db,
+ "SELECT 'DELETE FROM vacuum_db.' || quote(name) || ';' "
+ "FROM vacuum_db.sqlite_master WHERE name='sqlite_sequence' "
+ );
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = execExecSql(db,
+ "SELECT 'INSERT INTO vacuum_db.' || quote(name) "
+ "|| ' SELECT * FROM ' || quote(name) || ';' "
+ "FROM vacuum_db.sqlite_master WHERE name=='sqlite_sequence';"
+ );
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+
+ /* Copy the triggers, views, and virtual tables from the main database
+ ** over to the temporary database. None of these objects has any
+ ** associated storage, so all we have to do is copy their entries
+ ** from the SQLITE_MASTER table.
+ */
+ rc = execSql(db,
+ "INSERT INTO vacuum_db.sqlite_master "
+ " SELECT type, name, tbl_name, rootpage, sql"
+ " FROM sqlite_master"
+ " WHERE type='view' OR type='trigger'"
+ " OR (type='table' AND rootpage=0)"
+ );
+ if( rc ) goto end_of_vacuum;
+
+ /* At this point, unless the main db was completely empty, there is now a
+ ** transaction open on the vacuum database, but not on the main database.
+ ** Open a btree level transaction on the main database. This allows a
+ ** call to sqlite3BtreeCopyFile(). The main database btree level
+ ** transaction is then committed, so the SQL level never knows it was
+ ** opened for writing. This way, the SQL transaction used to create the
+ ** temporary database never needs to be committed.
+ */
+ if( rc==SQLITE_OK ){
+ u32 meta;
+ int i;
+
+ /* This array determines which meta meta values are preserved in the
+ ** vacuum. Even entries are the meta value number and odd entries
+ ** are an increment to apply to the meta value after the vacuum.
+ ** The increment is used to increase the schema cookie so that other
+ ** connections to the same database will know to reread the schema.
+ */
+ static const unsigned char aCopy[] = {
+ 1, 1, /* Add one to the old schema cookie */
+ 3, 0, /* Preserve the default page cache size */
+ 5, 0, /* Preserve the default text encoding */
+ 6, 0, /* Preserve the user version */
+ };
+
+ assert( 1==sqlite3BtreeIsInTrans(pTemp) );
+ assert( 1==sqlite3BtreeIsInTrans(pMain) );
+
+ /* Copy Btree meta values */
+ for(i=0; i<sizeof(aCopy)/sizeof(aCopy[0]); i+=2){
+ rc = sqlite3BtreeGetMeta(pMain, aCopy[i], &meta);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = sqlite3BtreeUpdateMeta(pTemp, aCopy[i], meta+aCopy[i+1]);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ }
+
+ rc = sqlite3BtreeCopyFile(pMain, pTemp);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = sqlite3BtreeCommit(pTemp);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = sqlite3BtreeCommit(pMain);
+ }
+
+end_of_vacuum:
+ /* Restore the original value of db->flags */
+ db->flags = saved_flags;
+
+ /* Currently there is an SQL level transaction open on the vacuum
+ ** database. No locks are held on any other files (since the main file
+ ** was committed at the btree level). So it safe to end the transaction
+ ** by manually setting the autoCommit flag to true and detaching the
+ ** vacuum database. The vacuum_db journal file is deleted when the pager
+ ** is closed by the DETACH.
+ */
+ db->autoCommit = 1;
+
+ if( pDb ){
+ sqlite3BtreeClose(pDb->pBt);
+ pDb->pBt = 0;
+ pDb->pSchema = 0;
+ }
+
+ sqlite3ResetInternalSchema(db, 0);
+
+ return rc;
+}
+#endif /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */