*************************************************************************
** This file contains code associated with the ANALYZE command.
**
-** @(#) $Id: analyze.c,v 1.1 2005/07/08 12:13:05 drh Exp $
+** @(#) $Id: analyze.c,v 1.2 2005/07/23 00:41:49 drh Exp $
*/
#ifndef SQLITE_OMIT_ANALYZE
#include "sqliteInt.h"
/*
-** Generate code for the ANALYZE command
+** This routine generates code that opens the sqlite_stat1 table on cursor
+** iStatCur.
+**
+** If the sqlite_stat1 tables does not previously exist, it is created.
+** If it does previously exist, all entires associated with table zWhere
+** are removed. If zWhere==0 then all entries are removed.
+*/
+static void openStatTable(
+ Parse *pParse, /* Parsing context */
+ int iDb, /* The database we are looking in */
+ int iStatCur, /* Open the sqlite_stat1 table on this cursor */
+ const char *zWhere /* Delete entries associated with this table */
+){
+ sqlite3 *db = pParse->db;
+ Db *pDb;
+ int iRootPage;
+ Table *pStat;
+ Vdbe *v = sqlite3GetVdbe(pParse);
+
+ pDb = &db->aDb[iDb];
+ if( (pStat = sqlite3FindTable(db, "sqlite_stat1", pDb->zName))==0 ){
+ /* The sqlite_stat1 tables does not exist. Create it.
+ ** Note that a side-effect of the CREATE TABLE statement is to leave
+ ** the rootpage of the new table on the top of the stack. This is
+ ** important because the OpenWrite opcode below will be needing it. */
+ sqlite3NestedParse(pParse,
+ "CREATE TABLE %Q.sqlite_stat1(tbl,idx,stat)",
+ pDb->zName
+ );
+ iRootPage = 0; /* Cause rootpage to be taken from top of stack */
+ }else if( zWhere ){
+ /* The sqlite_stat1 table exists. Delete all entries associated with
+ ** the table zWhere. */
+ sqlite3NestedParse(pParse,
+ "DELETE FROM %Q.sqlite_stat1 WHERE tbl=%Q",
+ pDb->zName, zWhere
+ );
+ iRootPage = pStat->tnum;
+ }else{
+ /* The sqlite_stat1 table already exists. Delete all rows. */
+ iRootPage = pStat->tnum;
+ sqlite3VdbeAddOp(v, OP_Clear, pStat->tnum, iDb);
+ }
+
+ /* Open the sqlite_stat1 table for writing.
+ */
+ sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
+ sqlite3VdbeAddOp(v, OP_OpenWrite, iStatCur, 0);
+ sqlite3VdbeAddOp(v, OP_SetNumColumns, iStatCur, 3);
+}
+
+/*
+** Generate code to do an analysis of all indices associated with
+** a single table.
+*/
+static void analyzeOneTable(
+ Parse *pParse, /* Parser context */
+ Table *pTab, /* Table whose indices are to be analyzed */
+ int iStatCur, /* Cursor that writes to the sqlite_stat1 table */
+ int iMem /* Available memory locations begin here */
+){
+ Index *pIdx; /* An index to being analyzed */
+ int iIdxCur; /* Cursor number for index being analyzed */
+ int nCol; /* Number of columns in the index */
+ Vdbe *v; /* The virtual machine being built up */
+ int i; /* Loop counter */
+ int topOfLoop; /* The top of the loop */
+ int endOfLoop; /* The end of the loop */
+ int addr; /* The address of an instruction */
+
+ v = sqlite3GetVdbe(pParse);
+ if( pTab==0 || pTab->pIndex==0 || pTab->pIndex->pNext==0 ){
+ /* Do no analysis for tables with fewer than 2 indices */
+ return;
+ }
+ iIdxCur = pParse->nTab;
+ for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+ /* Open a cursor to the index to be analyzed
+ */
+ sqlite3VdbeAddOp(v, OP_Integer, pIdx->iDb, 0);
+ VdbeComment((v, "# %s", pIdx->zName));
+ sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum,
+ (char*)&pIdx->keyInfo, P3_KEYINFO);
+ nCol = pIdx->nColumn;
+ if( iMem+nCol*2>=pParse->nMem ){
+ pParse->nMem = iMem+nCol*2+1;
+ }
+ sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, nCol+1);
+
+ /* Memory cells are used as follows:
+ **
+ ** mem[iMem]: The total number of rows in the table.
+ ** mem[iMem+1]: Number of distinct values in column 1
+ ** ...
+ ** mem[iMem+nCol]: Number of distinct values in column N
+ ** mem[iMem+nCol+1] Last observed value of column 1
+ ** ...
+ ** mem[iMem+nCol+nCol]: Last observed value of column N
+ **
+ ** Cells iMem through iMem+nCol are initialized to 0. The others
+ ** are initialized to NULL.
+ */
+ sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
+ for(i=0; i<=nCol; i++){
+ sqlite3VdbeAddOp(v, OP_MemStore, iMem+i, i==nCol);
+ }
+ sqlite3VdbeAddOp(v, OP_Null, 0, 0);
+ for(i=0; i<nCol; i++){
+ sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, i==nCol-1);
+ }
+
+ /* Do the analysis.
+ */
+ sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, 0);
+ topOfLoop = sqlite3VdbeCurrentAddr(v);
+ endOfLoop = sqlite3VdbeMakeLabel(v);
+ sqlite3VdbeAddOp(v, OP_MemIncr, iMem, 0);
+ for(i=0; i<nCol; i++){
+ sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
+ sqlite3VdbeAddOp(v, OP_MemLoad, iMem+nCol+i+1, 0);
+ sqlite3VdbeAddOp(v, OP_Ne, 0x100, 0);
+ }
+ sqlite3VdbeAddOp(v, OP_Goto, 0, endOfLoop);
+ for(i=0; i<nCol; i++){
+ addr = sqlite3VdbeAddOp(v, OP_MemIncr, iMem+i+1, 0);
+ sqlite3VdbeChangeP2(v, topOfLoop + 3*i + 3, addr);
+ sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
+ sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, 1);
+ }
+ sqlite3VdbeResolveLabel(v, endOfLoop);
+ sqlite3VdbeAddOp(v, OP_Next, iIdxCur, topOfLoop);
+ sqlite3VdbeAddOp(v, OP_Close, iIdxCur, 0);
+
+ /* Store the results.
+ **
+ ** The result is a single row of the sqlite_stmt1 table. The first
+ ** two columns are the names of the table and index. The third column
+ ** is a string composed of a list of integer statistics about the
+ ** index. There is one integer in the list for each column of the table.
+ ** This integer is a guess of how many rows of the table the index will
+ ** select. If D is the count of distinct values and K is the total
+ ** number of rows, then the integer is computed as:
+ **
+ ** I = (K+D-1)/D
+ **
+ ** If K==0 then no entry is made into the sqlite_stat1 table.
+ ** If K>0 then it is always the case the D>0 so division by zero
+ ** is never possible.
+ */
+ sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
+ addr = sqlite3VdbeAddOp(v, OP_IfNot, 0, 0);
+ sqlite3VdbeAddOp(v, OP_NewRowid, iStatCur, 0);
+ sqlite3VdbeOp3(v, OP_String8, 0, 0, pTab->zName, 0);
+ sqlite3VdbeOp3(v, OP_String8, 0, 0, pIdx->zName, 0);
+ for(i=0; i<nCol; i++){
+ sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
+ sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
+ sqlite3VdbeAddOp(v, OP_Add, 0, 0);
+ sqlite3VdbeAddOp(v, OP_AddImm, -1, 0);
+ sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
+ sqlite3VdbeAddOp(v, OP_Divide, 0, 0);
+ if( i==nCol-1 ){
+ if( i>0 ){
+ sqlite3VdbeAddOp(v, OP_Concat, nCol*2-3, 0);
+ }
+ }else{
+ if( i==0 ){
+ sqlite3VdbeOp3(v, OP_String8, 0, 0, " ", 0);
+ }else{
+ sqlite3VdbeAddOp(v, OP_Dup, 1, 0);
+ }
+ }
+ }
+ sqlite3VdbeOp3(v, OP_MakeRecord, 3, 0, "ttt", 0);
+ sqlite3VdbeAddOp(v, OP_Insert, iStatCur, 0);
+ sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v));
+ }
+}
+
+/*
+** Generate code that will do an analysis of an entire database
+*/
+static void analyzeDatabase(Parse *pParse, int iDb){
+ sqlite3 *db = pParse->db;
+ HashElem *k;
+ int iStatCur;
+ int iMem;
+
+ sqlite3BeginWriteOperation(pParse, 0, iDb);
+ iStatCur = pParse->nTab++;
+ openStatTable(pParse, iDb, iStatCur, 0);
+ iMem = pParse->nMem;
+ for(k=sqliteHashFirst(&db->aDb[iDb].tblHash); k; k=sqliteHashNext(k)){
+ Table *pTab = (Table*)sqliteHashData(k);
+ analyzeOneTable(pParse, pTab, iStatCur, iMem);
+ }
+}
+
+/*
+** Generate code that will do an analysis of a single table in
+** a database.
+*/
+static void analyzeTable(Parse *pParse, Table *pTab){
+ int iDb;
+ int iStatCur;
+
+ assert( pTab!=0 );
+ iDb = pTab->iDb;
+ sqlite3BeginWriteOperation(pParse, 0, iDb);
+ iStatCur = pParse->nTab++;
+ openStatTable(pParse, iDb, iStatCur, pTab->zName);
+ analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem);
+}
+
+/*
+** Generate code for the ANALYZE command. The parser calls this routine
+** when it recognizes an ANALYZE command.
**
** ANALYZE -- 1
-** ANALYZE <database > -- 2
+** ANALYZE <database> -- 2
** ANALYZE ?<database>.?<tablename> -- 3
**
** Form 1 causes all indices in all attached databases to be analyzed.
** Form 3 analyzes all indices associated with the named table.
*/
void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){
+ sqlite3 *db = pParse->db;
+ int iDb;
+ int i;
+ char *z, *zDb;
+ Table *pTab;
+ Token *pTableName;
+
+ /* Read the database schema. If an error occurs, leave an error message
+ ** and code in pParse and return NULL. */
+ if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
+ return;
+ }
+
+ if( pName1==0 ){
+ /* Form 1: Analyze everything */
+ for(i=0; i<db->nDb; i++){
+ if( i==1 ) continue; /* Do not analyze the TEMP database */
+ analyzeDatabase(pParse, i);
+ }
+ }else if( pName2==0 ){
+ /* Form 2: Analyze the database or table named */
+ iDb = sqlite3FindDb(db, pName1);
+ if( iDb>=0 ){
+ analyzeDatabase(pParse, iDb);
+ return;
+ }
+ z = sqlite3NameFromToken(pName1);
+ pTab = sqlite3LocateTable(pParse, z, 0);
+ sqliteFree(z);
+ if( pTab ){
+ analyzeTable(pParse, pTab);
+ }
+ return;
+ }else{
+ /* Form 3: Analyze the fully qualified table name */
+ iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
+ if( iDb>=0 ){
+ zDb = db->aDb[iDb].zName;
+ z = sqlite3NameFromToken(pTableName);
+ pTab = sqlite3LocateTable(pParse, z, zDb);
+ sqliteFree(z);
+ if( pTab ){
+ analyzeTable(pParse, pTab);
+ }
+ }
+ }
}
+
#endif /* SQLITE_OMIT_ANALYZE */
projects / thirdparty / sqlite.git / commitdiff
