/*

 ** 2005 July 8

 **

 ** 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 associated with the ANALYZE command.

 **

 ** @(#) $Id: analyze.c,v 1.43 2008/07/28 19:34:53 drh Exp $

 */

 #ifndef SQLITE_OMIT_ANALYZE

 #include "sqliteInt.h"

 /*

 ** 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;

   int createStat1 = 0;

   Table *pStat;

   Vdbe *v = sqlite3GetVdbe(pParse);

   if( v==0 ) return;

   assert( sqlite3BtreeHoldsAllMutexes(db) );

   assert( sqlite3VdbeDb(v)==db );

   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 in register pParse->regRoot.  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 = pParse->regRoot;

     createStat1 = 1;  /* 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;

     sqlite3VdbeAddOp2(v, OP_Clear, pStat->tnum, iDb);

   }

   /* Open the sqlite_stat1 table for writing. Unless it was created

   ** by this vdbe program, lock it for writing at the shared-cache level. 

   ** If this vdbe did create the sqlite_stat1 table, then it must have 

   ** already obtained a schema-lock, making the write-lock redundant.

   */

   if( !createStat1 ){

     sqlite3TableLock(pParse, iDb, iRootPage, 1, "sqlite_stat1");

   }

   sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, 3);

   sqlite3VdbeAddOp3(v, OP_OpenWrite, iStatCur, iRootPage, iDb);

   sqlite3VdbeChangeP5(v, createStat1);

 }

 /*

 ** 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 */

   int iDb;         /* Index of database containing pTab */

   v = sqlite3GetVdbe(pParse);

   if( v==0 || pTab==0 || pTab->pIndex==0 ){

     /* Do no analysis for tables that have no indices */

     return;

   }

   assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );

   iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

   assert( iDb>=0 );

 #ifndef SQLITE_OMIT_AUTHORIZATION

   if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,

       pParse->db->aDb[iDb].zName ) ){

     return;

   }

 #endif

   /* Establish a read-lock on the table at the shared-cache level. */

   sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);

   iIdxCur = pParse->nTab;

   for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){

     KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);

     int regFields;    /* Register block for building records */

     int regRec;       /* Register holding completed record */

     int regTemp;      /* Temporary use register */

     int regCol;       /* Content of a column from the table being analyzed */

     int regRowid;     /* Rowid for the inserted record */

     int regF2;

     /* Open a cursor to the index to be analyzed

     */

     assert( iDb==sqlite3SchemaToIndex(pParse->db, pIdx->pSchema) );

     nCol = pIdx->nColumn;

     sqlite3VdbeAddOp2(v, OP_SetNumColumns, 0, nCol+1);

     sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb,

         (char *)pKey, P4_KEYINFO_HANDOFF);

     VdbeComment((v, "%s", pIdx->zName));

     regFields = iMem+nCol*2;

     regTemp = regRowid = regCol = regFields+3;

     regRec = regCol+1;

     if( regRec>pParse->nMem ){

       pParse->nMem = regRec;

     }

     /* 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.

     */

     for(i=0; i<=nCol; i++){

       sqlite3VdbeAddOp2(v, OP_Integer, 0, iMem+i);

     }

     for(i=0; i<nCol; i++){

       sqlite3VdbeAddOp2(v, OP_Null, 0, iMem+nCol+i+1);

     }

     /* Do the analysis.

     */

     endOfLoop = sqlite3VdbeMakeLabel(v);

     sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);

     topOfLoop = sqlite3VdbeCurrentAddr(v);

     sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1);

     for(i=0; i<nCol; i++){

       sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);

       sqlite3VdbeAddOp3(v, OP_Ne, regCol, 0, iMem+nCol+i+1);

       /**** TODO:  add collating sequence *****/

       sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);

     }

     sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);

     for(i=0; i<nCol; i++){

       sqlite3VdbeJumpHere(v, topOfLoop + 2*(i + 1));

       sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1);

       sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1);

     }

     sqlite3VdbeResolveLabel(v, endOfLoop);

     sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, topOfLoop);

     sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);

     /* Store the results.  

     **

     ** The result is a single row of the sqlite_stat1 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.  The first integer in the list is the total number of entires

     ** in the index.  There is one additional integer in the list for each

     ** column of the table.  This additional 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.

     */

     addr = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);

     sqlite3VdbeAddOp4(v, OP_String8, 0, regFields, 0, pTab->zName, 0);

     sqlite3VdbeAddOp4(v, OP_String8, 0, regFields+1, 0, pIdx->zName, 0);

     regF2 = regFields+2;

     sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regF2);

     for(i=0; i<nCol; i++){

       sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);

       sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regF2, regF2);

       sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);

       sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);

       sqlite3VdbeAddOp3(v, OP_Divide, iMem+i+1, regTemp, regTemp);

       sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);

       sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regF2, regF2);

     }

     sqlite3VdbeAddOp4(v, OP_MakeRecord, regFields, 3, regRec, "aaa", 0);

     sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);

     sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);

     sqlite3VdbeChangeP5(v, OPFLAG_APPEND);

     sqlite3VdbeJumpHere(v, addr);

   }

 }

 /*

 ** Generate code that will cause the most recent index analysis to

 ** be laoded into internal hash tables where is can be used.

 */

 static void loadAnalysis(Parse *pParse, int iDb){

   Vdbe *v = sqlite3GetVdbe(pParse);

   if( v ){

     sqlite3VdbeAddOp1(v, OP_LoadAnalysis, iDb);

   }

 }

 /*

 ** Generate code that will do an analysis of an entire database

 */

 static void analyzeDatabase(Parse *pParse, int iDb){

   sqlite3 *db = pParse->db;

   Schema *pSchema = db->aDb[iDb].pSchema;    /* Schema of database iDb */

   HashElem *k;

   int iStatCur;

   int iMem;

   sqlite3BeginWriteOperation(pParse, 0, iDb);

   iStatCur = pParse->nTab++;

   openStatTable(pParse, iDb, iStatCur, 0);

   iMem = pParse->nMem+1;

   for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){

     Table *pTab = (Table*)sqliteHashData(k);

     analyzeOneTable(pParse, pTab, iStatCur, iMem);

   }

   loadAnalysis(pParse, iDb);

 }

 /*

 ** 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 );

   assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );

   iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);

   sqlite3BeginWriteOperation(pParse, 0, iDb);

   iStatCur = pParse->nTab++;

   openStatTable(pParse, iDb, iStatCur, pTab->zName);

   analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem+1);

   loadAnalysis(pParse, iDb);

 }

 /*

 ** Generate code for the ANALYZE command.  The parser calls this routine

 ** when it recognizes an ANALYZE command.

 **

 **        ANALYZE                            -- 1

 **        ANALYZE  <database>                -- 2

 **        ANALYZE  ?<database>.?<tablename>  -- 3

 **

 ** Form 1 causes all indices in all attached databases to be analyzed.

 ** Form 2 analyzes all indices the single database named.

 ** 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. */

   assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );

   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 || pName2->n==0 ){

     /* Form 2:  Analyze the database or table named */

     iDb = sqlite3FindDb(db, pName1);

     if( iDb>=0 ){

       analyzeDatabase(pParse, iDb);

     }else{

       z = sqlite3NameFromToken(db, pName1);

       if( z ){

         pTab = sqlite3LocateTable(pParse, 0, z, 0);

         sqlite3DbFree(db, z);

         if( pTab ){

           analyzeTable(pParse, pTab);

         }

       }

     }

   }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(db, pTableName);

       if( z ){

         pTab = sqlite3LocateTable(pParse, 0, z, zDb);

         sqlite3DbFree(db, z);

         if( pTab ){

           analyzeTable(pParse, pTab);

         }

       }

     }   

   }

 }

 /*

 ** Used to pass information from the analyzer reader through to the

 ** callback routine.

 */

 typedef struct analysisInfo analysisInfo;

 struct analysisInfo {

   sqlite3 *db;

   const char *zDatabase;

 };

 /*

 ** This callback is invoked once for each index when reading the

 ** sqlite_stat1 table.  

 **

 **     argv[0] = name of the index

 **     argv[1] = results of analysis - on integer for each column

 */

 static int analysisLoader(void *pData, int argc, char **argv, char **azNotUsed){

   analysisInfo *pInfo = (analysisInfo*)pData;

   Index *pIndex;

   int i, c;

   unsigned int v;

   const char *z;

   assert( argc==2 );

   if( argv==0 || argv[0]==0 || argv[1]==0 ){

     return 0;

   }

   pIndex = sqlite3FindIndex(pInfo->db, argv[0], pInfo->zDatabase);

   if( pIndex==0 ){

     return 0;

   }

   z = argv[1];

   for(i=0; *z && i<=pIndex->nColumn; i++){

     v = 0;

     while( (c=z[0])>='0' && c<='9' ){

       v = v*10 + c - '0';

       z++;

     }

     pIndex->aiRowEst[i] = v;

     if( *z==' ' ) z++;

   }

   return 0;

 }

 /*

 ** Load the content of the sqlite_stat1 table into the index hash tables.

 */

 int sqlite3AnalysisLoad(sqlite3 *db, int iDb){

   analysisInfo sInfo;

   HashElem *i;

   char *zSql;

   int rc;

   assert( iDb>=0 && iDb<db->nDb );

   assert( db->aDb[iDb].pBt!=0 );

   assert( sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );

   /* Clear any prior statistics */

   for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){

     Index *pIdx = sqliteHashData(i);

     sqlite3DefaultRowEst(pIdx);

   }

   /* Check to make sure the sqlite_stat1 table existss */

   sInfo.db = db;

   sInfo.zDatabase = db->aDb[iDb].zName;

   if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){

      return SQLITE_ERROR;

   }

   /* Load new statistics out of the sqlite_stat1 table */

   zSql = sqlite3MPrintf(db, "SELECT idx, stat FROM %Q.sqlite_stat1",

                         sInfo.zDatabase);

   (void)sqlite3SafetyOff(db);

   rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);

   (void)sqlite3SafetyOn(db);

   sqlite3DbFree(db, zSql);

   return rc;

 }

 #endif /* SQLITE_OMIT_ANALYZE */