e883f21fe8
Files correlati : sqlite Ricompilazione Demo : [ ] Commento : Passaggio da Sqlite 2 a Sqlite 3.3.5 git-svn-id: svn://10.65.10.50/trunk@13902 c028cbd2-c16b-5b4b-a496-9718f37d4682
330 lines
11 KiB
C
Executable File
330 lines
11 KiB
C
Executable File
/*
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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: vacuum.c,v 1.2 2006-04-13 12:44:29 guy Exp $
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*/
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#include "sqliteInt.h"
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#include "vdbeInt.h"
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#include "os.h"
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#ifndef SQLITE_OMIT_VACUUM
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/*
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** Generate a random name of 20 character in length.
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*/
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static void randomName(unsigned char *zBuf){
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static const unsigned char zChars[] =
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"abcdefghijklmnopqrstuvwxyz"
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"0123456789";
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int i;
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sqlite3Randomness(20, zBuf);
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for(i=0; i<20; i++){
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zBuf[i] = zChars[ zBuf[i]%(sizeof(zChars)-1) ];
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}
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}
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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( 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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#endif
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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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#ifndef SQLITE_OMIT_VACUUM
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const char *zFilename; /* full pathname of the database file */
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int nFilename; /* number of characters in zFilename[] */
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char *zTemp = 0; /* a temporary file in same directory as zFilename */
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Btree *pMain; /* The database being vacuumed */
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Btree *pTemp;
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char *zSql = 0;
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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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/* Get the full pathname of the database file and create a
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** temporary filename in the same directory as the original file.
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*/
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pMain = db->aDb[0].pBt;
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zFilename = sqlite3BtreeGetFilename(pMain);
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assert( zFilename );
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if( zFilename[0]=='\0' ){
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/* The in-memory database. Do nothing. Return directly to avoid causing
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** an error trying to DETACH the vacuum_db (which never got attached)
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** in the exit-handler.
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*/
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return SQLITE_OK;
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}
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nFilename = strlen(zFilename);
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zTemp = sqliteMalloc( nFilename+100 );
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if( zTemp==0 ){
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rc = SQLITE_NOMEM;
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goto end_of_vacuum;
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}
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strcpy(zTemp, zFilename);
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/* The randomName() procedure in the following loop uses an excellent
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** source of randomness to generate a name from a space of 1.3e+31
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** possibilities. So unless the directory already contains on the order
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** of 1.3e+31 files, the probability that the following loop will
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** run more than once or twice is vanishingly small. We are certain
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** enough that this loop will always terminate (and terminate quickly)
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** that we don't even bother to set a maximum loop count.
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*/
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do {
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zTemp[nFilename] = '-';
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randomName((unsigned char*)&zTemp[nFilename+1]);
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} while( sqlite3OsFileExists(zTemp) );
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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 = sqlite3MPrintf("ATTACH '%q' AS vacuum_db;", zTemp);
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if( !zSql ){
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rc = SQLITE_NOMEM;
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goto end_of_vacuum;
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}
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rc = execSql(db, zSql);
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sqliteFree(zSql);
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zSql = 0;
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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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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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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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rc = execExecSql(db,
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"SELECT 'CREATE VIEW vacuum_db.' || substr(sql,13,100000000) "
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" FROM sqlite_master WHERE type='view'"
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);
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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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);
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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 from the main database to the temporary database.
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** This was deferred before in case the triggers interfered with copying
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** the data. It's possible the indices should be deferred until this
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** point also.
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*/
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rc = execExecSql(db,
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"SELECT 'CREATE TRIGGER vacuum_db.' || substr(sql, 16, 1000000) "
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"FROM sqlite_master WHERE type='trigger'"
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);
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if( rc!=SQLITE_OK ) 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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sqlite3MallocDisallow();
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sqlite3BtreeClose(pDb->pBt);
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sqlite3MallocAllow();
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pDb->pBt = 0;
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pDb->pSchema = 0;
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}
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/* If one of the execSql() calls above returned SQLITE_NOMEM, then the
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** mallocFailed flag will be clear (because execSql() calls sqlite3_exec()).
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** Fix this so the flag and return code match.
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*/
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if( rc==SQLITE_NOMEM ){
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sqlite3MallocFailed();
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}
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if( zTemp ){
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sqlite3OsDelete(zTemp);
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sqliteFree(zTemp);
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}
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sqliteFree( zSql );
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sqlite3ResetInternalSchema(db, 0);
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#endif
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return rc;
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}
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