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+/*
+** 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 548347 2006-06-05 10:53:00Z staniek $
+*/
+#include "sqliteInt.h"
+#include "os.h"
+
+#ifndef SQLITE_OMIT_VACUUM
+/*
+** Generate a random name of 20 character in length.
+*/
+static void randomName(unsigned char *zBuf){
+ static const unsigned char zChars[] =
+ "abcdefghijklmnopqrstuvwxyz"
+ "0123456789";
+ int i;
+ sqlite3Randomness(20, zBuf);
+ for(i=0; i<20; i++){
+ zBuf[i] = zChars[ zBuf[i]%(sizeof(zChars)-1) ];
+ }
+}
+
+/*
+** 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);
+}
+
+/* (jstaniek) */
+extern int g_verbose_vacuum;
+
+/*
+** Execute zSql on database db. The statement returns exactly
+** one column. Execute this as SQL on the same database.
+**
+** (js: extension): if count > 0, "VACUUM: X%" string will
+** be printed to stdout, so user (a human or calling application)
+** can know the overall progress of the operation.
+** and the program will wait for a key press (followed by RETURN);
+** 'q' key aborts the execution and any other key allows to proceed.
+*/
+static int execExecSql(sqlite3 *db, const char *zSql, int count){
+ sqlite3_stmt *pStmt;
+ int rc, i;
+ char ch;
+
+ rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
+ if( rc!=SQLITE_OK ) return rc;
+
+ for( i=0; SQLITE_ROW==sqlite3_step(pStmt); i++ ){
+ if (g_verbose_vacuum!=0 && count>0) {
+ fprintf(stdout, "VACUUM: %d%%\n", 100*(i+1)/count);
+ fflush(stdout);
+ fscanf(stdin, "%c", &ch);
+ if ('q'==ch) { /* quit */
+ sqlite3_finalize(pStmt);
+ return SQLITE_ABORT;
+ }
+ }
+ rc = execSql(db, sqlite3_column_text(pStmt, 0));
+ if( rc!=SQLITE_OK ){
+ sqlite3_finalize(pStmt);
+ return rc;
+ }
+ }
+
+ return sqlite3_finalize(pStmt);
+}
+
+#endif
+
+/*
+** 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, Token *pTableName){
+ 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 */
+ sqlite3_stmt *pStmt = 0;
+ int tables_count = 0;
+#ifndef SQLITE_OMIT_VACUUM
+ const char *zFilename; /* full pathname of the database file */
+ int nFilename; /* number of characters in zFilename[] */
+ char *zTemp = 0; /* a temporary file in same directory as zFilename */
+ Btree *pMain; /* The database being vacuumed */
+ Btree *pTemp;
+ char *zSql = 0;
+ int writeschema_flag; /* Saved value of the write-schema flag */
+
+ /* Save the current value of the write-schema flag before setting it. */
+ writeschema_flag = db->flags&SQLITE_WriteSchema;
+ db->flags |= SQLITE_WriteSchema;
+
+ if( !db->autoCommit ){
+ sqlite3SetString(pzErrMsg, "cannot VACUUM from within a transaction",
+ (char*)0);
+ rc = SQLITE_ERROR;
+ goto end_of_vacuum;
+ }
+
+ /* Get the full pathname of the database file and create a
+ ** temporary filename in the same directory as the original file.
+ */
+ pMain = db->aDb[0].pBt;
+ zFilename = sqlite3BtreeGetFilename(pMain);
+ assert( zFilename );
+ if( zFilename[0]=='\0' ){
+ /* The in-memory database. Do nothing. Return directly to avoid causing
+ ** an error trying to DETACH the vacuum_db (which never got attached)
+ ** in the exit-handler.
+ */
+ return SQLITE_OK;
+ }
+ nFilename = strlen(zFilename);
+ zTemp = sqliteMalloc( nFilename+100 );
+ if( zTemp==0 ){
+ rc = SQLITE_NOMEM;
+ goto end_of_vacuum;
+ }
+ strcpy(zTemp, zFilename);
+
+ /* The randomName() procedure in the following loop uses an excellent
+ ** source of randomness to generate a name from a space of 1.3e+31
+ ** possibilities. So unless the directory already contains on the order
+ ** of 1.3e+31 files, the probability that the following loop will
+ ** run more than once or twice is vanishingly small. We are certain
+ ** enough that this loop will always terminate (and terminate quickly)
+ ** that we don't even bother to set a maximum loop count.
+ */
+ do {
+ zTemp[nFilename] = '-';
+ randomName((unsigned char*)&zTemp[nFilename+1]);
+ } while( sqlite3OsFileExists(zTemp) );
+
+ /* 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 = sqlite3MPrintf("ATTACH '%q' AS vacuum_db;", zTemp);
+ if( !zSql ){
+ rc = SQLITE_NOMEM;
+ goto end_of_vacuum;
+ }
+ rc = execSql(db, zSql);
+ sqliteFree(zSql);
+ zSql = 0;
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ assert( strcmp(db->aDb[db->nDb-1].zName,"vacuum_db")==0 );
+ pTemp = db->aDb[db->nDb-1].pBt;
+ sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain),
+ sqlite3BtreeGetReserve(pMain));
+ assert( sqlite3BtreeGetPageSize(pTemp)==sqlite3BtreeGetPageSize(pMain) );
+ execSql(db, "PRAGMA vacuum_db.synchronous=OFF");
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ sqlite3BtreeSetAutoVacuum(pTemp, sqlite3BtreeGetAutoVacuum(pMain));
+#endif
+
+ /* Begin a transaction */
+ rc = execSql(db, "BEGIN;");
+ 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'", 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 %' ", 0);
+ 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 %'", 0);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = execExecSql(db,
+ "SELECT 'CREATE VIEW vacuum_db.' || substr(sql,13,100000000) "
+ " FROM sqlite_master WHERE type='view'", 0
+ );
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+ /* (js) get # of tables so we can output progress.
+ */
+ rc = sqlite3_prepare(db, "SELECT count(name) FROM sqlite_master "
+ "WHERE type = 'table';", -1, &pStmt, 0);
+ if( rc!=SQLITE_OK || SQLITE_ROW!=sqlite3_step(pStmt)) goto end_of_vacuum;
+ tables_count = atoi( sqlite3_column_text(pStmt, 0) );
+
+ /* 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';", tables_count
+ );
+ 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' ", 0
+ );
+ 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';", 0
+ );
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+
+ /* Copy the triggers from the main database to the temporary database.
+ ** This was deferred before in case the triggers interfered with copying
+ ** the data. It's possible the indices should be deferred until this
+ ** point also.
+ */
+ rc = execExecSql(db,
+ "SELECT 'CREATE TRIGGER vacuum_db.' || substr(sql, 16, 1000000) "
+ "FROM sqlite_master WHERE type='trigger'", 0
+ );
+ if( rc!=SQLITE_OK ) 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( sqlite3BtreeIsInTrans(pTemp) ){
+ 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( 0==sqlite3BtreeIsInTrans(pMain) );
+ rc = sqlite3BtreeBeginTrans(pMain, 1);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+
+ /* 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]);
+ }
+
+ rc = sqlite3BtreeCopyFile(pMain, pTemp);
+ if( rc!=SQLITE_OK ) goto end_of_vacuum;
+ rc = sqlite3BtreeCommit(pMain);
+ }
+
+end_of_vacuum:
+ /* Restore the original value of the write-schema flag. */
+ db->flags &= ~SQLITE_WriteSchema;
+ db->flags |= writeschema_flag;
+
+ /* 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( rc==SQLITE_OK ){
+ rc = execSql(db, "DETACH vacuum_db;");
+ }else{
+ execSql(db, "DETACH vacuum_db;");
+ }
+ if( zTemp ){
+ sqlite3OsDelete(zTemp);
+ sqliteFree(zTemp);
+ }
+ if( zSql ) sqliteFree( zSql );
+ sqlite3ResetInternalSchema(db, 0);
+#endif
+
+ return rc;
+}
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