1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/extensions/sqlite/sqlite-source/vacuum.c Sun Jul 29 01:15:31 2007 +0000
1.3 @@ -0,0 +1,262 @@
1.4 +/*
1.5 +** 2003 April 6
1.6 +**
1.7 +** The author disclaims copyright to this source code. In place of
1.8 +** a legal notice, here is a blessing:
1.9 +**
1.10 +** May you do good and not evil.
1.11 +** May you find forgiveness for yourself and forgive others.
1.12 +** May you share freely, never taking more than you give.
1.13 +**
1.14 +*************************************************************************
1.15 +** This file contains code used to implement the VACUUM command.
1.16 +**
1.17 +** Most of the code in this file may be omitted by defining the
1.18 +** SQLITE_OMIT_VACUUM macro.
1.19 +**
1.20 +** $Id$
1.21 +*/
1.22 +#include "sqliteInt.h"
1.23 +#include "vdbeInt.h"
1.24 +#include "os.h"
1.25 +
1.26 +#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
1.27 +/*
1.28 +** Execute zSql on database db. Return an error code.
1.29 +*/
1.30 +static int execSql(sqlite3 *db, const char *zSql){
1.31 + sqlite3_stmt *pStmt;
1.32 + if( SQLITE_OK!=sqlite3_prepare(db, zSql, -1, &pStmt, 0) ){
1.33 + return sqlite3_errcode(db);
1.34 + }
1.35 + while( SQLITE_ROW==sqlite3_step(pStmt) ){}
1.36 + return sqlite3_finalize(pStmt);
1.37 +}
1.38 +
1.39 +/*
1.40 +** Execute zSql on database db. The statement returns exactly
1.41 +** one column. Execute this as SQL on the same database.
1.42 +*/
1.43 +static int execExecSql(sqlite3 *db, const char *zSql){
1.44 + sqlite3_stmt *pStmt;
1.45 + int rc;
1.46 +
1.47 + rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
1.48 + if( rc!=SQLITE_OK ) return rc;
1.49 +
1.50 + while( SQLITE_ROW==sqlite3_step(pStmt) ){
1.51 + rc = execSql(db, (char*)sqlite3_column_text(pStmt, 0));
1.52 + if( rc!=SQLITE_OK ){
1.53 + sqlite3_finalize(pStmt);
1.54 + return rc;
1.55 + }
1.56 + }
1.57 +
1.58 + return sqlite3_finalize(pStmt);
1.59 +}
1.60 +
1.61 +/*
1.62 +** The non-standard VACUUM command is used to clean up the database,
1.63 +** collapse free space, etc. It is modelled after the VACUUM command
1.64 +** in PostgreSQL.
1.65 +**
1.66 +** In version 1.0.x of SQLite, the VACUUM command would call
1.67 +** gdbm_reorganize() on all the database tables. But beginning
1.68 +** with 2.0.0, SQLite no longer uses GDBM so this command has
1.69 +** become a no-op.
1.70 +*/
1.71 +void sqlite3Vacuum(Parse *pParse){
1.72 + Vdbe *v = sqlite3GetVdbe(pParse);
1.73 + if( v ){
1.74 + sqlite3VdbeAddOp(v, OP_Vacuum, 0, 0);
1.75 + }
1.76 + return;
1.77 +}
1.78 +
1.79 +/*
1.80 +** This routine implements the OP_Vacuum opcode of the VDBE.
1.81 +*/
1.82 +int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
1.83 + int rc = SQLITE_OK; /* Return code from service routines */
1.84 + Btree *pMain; /* The database being vacuumed */
1.85 + Btree *pTemp; /* The temporary database we vacuum into */
1.86 + char *zSql = 0; /* SQL statements */
1.87 + int saved_flags; /* Saved value of the db->flags */
1.88 + Db *pDb = 0; /* Database to detach at end of vacuum */
1.89 +
1.90 + /* Save the current value of the write-schema flag before setting it. */
1.91 + saved_flags = db->flags;
1.92 + db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks;
1.93 +
1.94 + if( !db->autoCommit ){
1.95 + sqlite3SetString(pzErrMsg, "cannot VACUUM from within a transaction",
1.96 + (char*)0);
1.97 + rc = SQLITE_ERROR;
1.98 + goto end_of_vacuum;
1.99 + }
1.100 + pMain = db->aDb[0].pBt;
1.101 +
1.102 + /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
1.103 + ** can be set to 'off' for this file, as it is not recovered if a crash
1.104 + ** occurs anyway. The integrity of the database is maintained by a
1.105 + ** (possibly synchronous) transaction opened on the main database before
1.106 + ** sqlite3BtreeCopyFile() is called.
1.107 + **
1.108 + ** An optimisation would be to use a non-journaled pager.
1.109 + */
1.110 + zSql = "ATTACH '' AS vacuum_db;";
1.111 + rc = execSql(db, zSql);
1.112 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.113 + pDb = &db->aDb[db->nDb-1];
1.114 + assert( strcmp(db->aDb[db->nDb-1].zName,"vacuum_db")==0 );
1.115 + pTemp = db->aDb[db->nDb-1].pBt;
1.116 + sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain),
1.117 + sqlite3BtreeGetReserve(pMain));
1.118 + if( sqlite3MallocFailed() ){
1.119 + rc = SQLITE_NOMEM;
1.120 + goto end_of_vacuum;
1.121 + }
1.122 + assert( sqlite3BtreeGetPageSize(pTemp)==sqlite3BtreeGetPageSize(pMain) );
1.123 + rc = execSql(db, "PRAGMA vacuum_db.synchronous=OFF");
1.124 + if( rc!=SQLITE_OK ){
1.125 + goto end_of_vacuum;
1.126 + }
1.127 +
1.128 +#ifndef SQLITE_OMIT_AUTOVACUUM
1.129 + sqlite3BtreeSetAutoVacuum(pTemp, sqlite3BtreeGetAutoVacuum(pMain));
1.130 +#endif
1.131 +
1.132 + /* Begin a transaction */
1.133 + rc = execSql(db, "BEGIN EXCLUSIVE;");
1.134 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.135 +
1.136 + /* Query the schema of the main database. Create a mirror schema
1.137 + ** in the temporary database.
1.138 + */
1.139 + rc = execExecSql(db,
1.140 + "SELECT 'CREATE TABLE vacuum_db.' || substr(sql,14,100000000) "
1.141 + " FROM sqlite_master WHERE type='table' AND name!='sqlite_sequence'"
1.142 + " AND rootpage>0"
1.143 + );
1.144 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.145 + rc = execExecSql(db,
1.146 + "SELECT 'CREATE INDEX vacuum_db.' || substr(sql,14,100000000)"
1.147 + " FROM sqlite_master WHERE sql LIKE 'CREATE INDEX %' ");
1.148 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.149 + rc = execExecSql(db,
1.150 + "SELECT 'CREATE UNIQUE INDEX vacuum_db.' || substr(sql,21,100000000) "
1.151 + " FROM sqlite_master WHERE sql LIKE 'CREATE UNIQUE INDEX %'");
1.152 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.153 +
1.154 + /* Loop through the tables in the main database. For each, do
1.155 + ** an "INSERT INTO vacuum_db.xxx SELECT * FROM xxx;" to copy
1.156 + ** the contents to the temporary database.
1.157 + */
1.158 + rc = execExecSql(db,
1.159 + "SELECT 'INSERT INTO vacuum_db.' || quote(name) "
1.160 + "|| ' SELECT * FROM ' || quote(name) || ';'"
1.161 + "FROM sqlite_master "
1.162 + "WHERE type = 'table' AND name!='sqlite_sequence' "
1.163 + " AND rootpage>0"
1.164 +
1.165 + );
1.166 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.167 +
1.168 + /* Copy over the sequence table
1.169 + */
1.170 + rc = execExecSql(db,
1.171 + "SELECT 'DELETE FROM vacuum_db.' || quote(name) || ';' "
1.172 + "FROM vacuum_db.sqlite_master WHERE name='sqlite_sequence' "
1.173 + );
1.174 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.175 + rc = execExecSql(db,
1.176 + "SELECT 'INSERT INTO vacuum_db.' || quote(name) "
1.177 + "|| ' SELECT * FROM ' || quote(name) || ';' "
1.178 + "FROM vacuum_db.sqlite_master WHERE name=='sqlite_sequence';"
1.179 + );
1.180 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.181 +
1.182 +
1.183 + /* Copy the triggers, views, and virtual tables from the main database
1.184 + ** over to the temporary database. None of these objects has any
1.185 + ** associated storage, so all we have to do is copy their entries
1.186 + ** from the SQLITE_MASTER table.
1.187 + */
1.188 + rc = execSql(db,
1.189 + "INSERT INTO vacuum_db.sqlite_master "
1.190 + " SELECT type, name, tbl_name, rootpage, sql"
1.191 + " FROM sqlite_master"
1.192 + " WHERE type='view' OR type='trigger'"
1.193 + " OR (type='table' AND rootpage=0)"
1.194 + );
1.195 + if( rc ) goto end_of_vacuum;
1.196 +
1.197 + /* At this point, unless the main db was completely empty, there is now a
1.198 + ** transaction open on the vacuum database, but not on the main database.
1.199 + ** Open a btree level transaction on the main database. This allows a
1.200 + ** call to sqlite3BtreeCopyFile(). The main database btree level
1.201 + ** transaction is then committed, so the SQL level never knows it was
1.202 + ** opened for writing. This way, the SQL transaction used to create the
1.203 + ** temporary database never needs to be committed.
1.204 + */
1.205 + if( rc==SQLITE_OK ){
1.206 + u32 meta;
1.207 + int i;
1.208 +
1.209 + /* This array determines which meta meta values are preserved in the
1.210 + ** vacuum. Even entries are the meta value number and odd entries
1.211 + ** are an increment to apply to the meta value after the vacuum.
1.212 + ** The increment is used to increase the schema cookie so that other
1.213 + ** connections to the same database will know to reread the schema.
1.214 + */
1.215 + static const unsigned char aCopy[] = {
1.216 + 1, 1, /* Add one to the old schema cookie */
1.217 + 3, 0, /* Preserve the default page cache size */
1.218 + 5, 0, /* Preserve the default text encoding */
1.219 + 6, 0, /* Preserve the user version */
1.220 + };
1.221 +
1.222 + assert( 1==sqlite3BtreeIsInTrans(pTemp) );
1.223 + assert( 1==sqlite3BtreeIsInTrans(pMain) );
1.224 +
1.225 + /* Copy Btree meta values */
1.226 + for(i=0; i<sizeof(aCopy)/sizeof(aCopy[0]); i+=2){
1.227 + rc = sqlite3BtreeGetMeta(pMain, aCopy[i], &meta);
1.228 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.229 + rc = sqlite3BtreeUpdateMeta(pTemp, aCopy[i], meta+aCopy[i+1]);
1.230 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.231 + }
1.232 +
1.233 + rc = sqlite3BtreeCopyFile(pMain, pTemp);
1.234 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.235 + rc = sqlite3BtreeCommit(pTemp);
1.236 + if( rc!=SQLITE_OK ) goto end_of_vacuum;
1.237 + rc = sqlite3BtreeCommit(pMain);
1.238 + }
1.239 +
1.240 +end_of_vacuum:
1.241 + /* Restore the original value of db->flags */
1.242 + db->flags = saved_flags;
1.243 +
1.244 + /* Currently there is an SQL level transaction open on the vacuum
1.245 + ** database. No locks are held on any other files (since the main file
1.246 + ** was committed at the btree level). So it safe to end the transaction
1.247 + ** by manually setting the autoCommit flag to true and detaching the
1.248 + ** vacuum database. The vacuum_db journal file is deleted when the pager
1.249 + ** is closed by the DETACH.
1.250 + */
1.251 + db->autoCommit = 1;
1.252 +
1.253 + if( pDb ){
1.254 + sqlite3MallocDisallow();
1.255 + sqlite3BtreeClose(pDb->pBt);
1.256 + sqlite3MallocAllow();
1.257 + pDb->pBt = 0;
1.258 + pDb->pSchema = 0;
1.259 + }
1.260 +
1.261 + sqlite3ResetInternalSchema(db, 0);
1.262 +
1.263 + return rc;
1.264 +}
1.265 +#endif /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */
