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Diffstat (limited to 'third_party/sqlite/vacuum.c')
| -rw-r--r-- | third_party/sqlite/vacuum.c | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/third_party/sqlite/vacuum.c b/third_party/sqlite/vacuum.c new file mode 100644 index 0000000..e34a4e9 --- /dev/null +++ b/third_party/sqlite/vacuum.c @@ -0,0 +1,262 @@ +/* +** 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.c,v 1.69 2007/03/27 16:19:52 danielk1977 Exp $ +*/ +#include "sqliteInt.h" +#include "vdbeInt.h" +#include "os.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( 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( sqlite3MallocFailed() ){ + 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, 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,14,100000000) " + " 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,14,100000000)" + " 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,21,100000000) " + " 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 ){ + sqlite3MallocDisallow(); + sqlite3BtreeClose(pDb->pBt); + sqlite3MallocAllow(); + pDb->pBt = 0; + pDb->pSchema = 0; + } + + sqlite3ResetInternalSchema(db, 0); + + return rc; +} +#endif /* SQLITE_OMIT_VACUUM && SQLITE_OMIT_ATTACH */ |