SQLite

/* #define SQLITE_IGNORE 2 // Also used by sqlite3_authorizer() callback */
#define SQLITE_FAIL     3
/* #define SQLITE_ABORT 4  // Also an error code */
#define SQLITE_REPLACE  5


/*
** CAPI3REF: Prepared Statement Scan Statuses
**
** Return status data for a single loop within query pStmt.
**
** Parameter "idx" identifies the specific loop to retrieve statistics for.
** Loops are numbered starting from zero. If idx is out of range - less than
** zero or greater than or equal to the total number of loops used to implement
** the statement - a non-zero value is returned. In this case the final value
** of all five output parameters is undefined. Otherwise, if idx is in range,
** zero is returned and the output parameters set as follows:
**
** <ul>
**   <li> (*pnLoop) is set to the total number of times the loop has been run.
**   <li> (*pnVisit) is set to the total number of rows visited by the loop.
**   <li> (*pnEst) is set to the estimate of the number of rows visited
**        by each run of the loop used by the SQL optimizer. Ideally, this
**        value should be close to (*pnVisit)/(*pnLoop).
**   <li> (*pzName) is set to point to a nul-terminated string containing the
**        name of the index of table used by this loop.
**   <li> (*pzExplain) is set to point to a nul-terminated string containing 
**        same text that would be returned for this loop by an EXPLAIN
**        QUERY PLAN command.
** </ul>
**
** Output parameters *pzName and *pzExplain are set to point to buffers 
** managed by the statement object. Both of these pointers may be invalidated
** by any API call on the same statement object, including an sqlite3_step()
** sqlite3_bind_*() call.
**
** Statistics may not be available for all loops in all statements. In cases
** where there exist loops with no available statistics, this function ignores
** them completely.
**
** This API is only available if the library is built with pre-processor
** symbol SQLITE_ENABLE_STMT_SCANSTATUS defined.
*/
SQLITE_EXPERIMENTAL int sqlite3_stmt_scanstatus(
  sqlite3_stmt *pStmt,
  int idx,                        /* Index of loop to report on */
  sqlite3_int64 *pnLoop,          /* OUT: Number of times loop was run */
  sqlite3_int64 *pnVisit,         /* OUT: Number of rows visited (all loops) */
  sqlite3_int64 *pnEst,           /* OUT: Number of rows estimated (per loop) */
  const char **pzName,            /* OUT: Object name (table or index) */
  const char **pzExplain          /* OUT: EQP string */
);


/*
** CAPI3REF: Zero Scan-Status Counters
**
** Zero all sqlite3_stmt_scanstatus() related event counters.
**
** This API is only available if the library is built with pre-processor
** symbol SQLITE_ENABLE_STMT_SCANSTATUS defined.
*/
SQLITE_EXPERIMENTAL void sqlite3_stmt_scanstatus_reset(sqlite3_stmt*);

  assert( pC->isTable );
  assert( pC->pseudoTableReg==0 );
  pCrsr = pC->pCursor;
  assert( pCrsr!=0 );
  res = 0;
  iKey = pIn3->u.i;
  rc = sqlite3BtreeMovetoUnpacked(pCrsr, 0, iKey, 0, &res);
  IncrementExplainCounter(pC, nLoop);
  pC->movetoTarget = iKey;  /* Used by OP_Delete */
  pC->nullRow = 0;
  pC->cacheStatus = CACHE_STALE;
  pC->deferredMoveto = 0;
  VdbeBranchTaken(res!=0,2);
  if( res!=0 ){
    pc = pOp->p2 - 1;
  }else{
    IncrementExplainCounter(pC, nVisit);
  }
  pC->seekResult = res;
  break;
}

/* Opcode: Sequence P1 P2 * * *
** Synopsis: r[P2]=cursor[P1].ctr++

      }
    }
  }
  *pzAff = zAff;
  return regBase;
}

#if !defined(SQLITE_OMIT_EXPLAIN) || defined(SQLITE_ENABLE_STMT_SCANSTATUS)
/*
** This routine is a helper for explainIndexRange() below
**
** pStr holds the text of an expression that we are building up one term
** at a time.  This routine adds a new term to the end of the expression.
** Terms are separated by AND so add the "AND" text for second and subsequent
** terms only.

** command. If the query being compiled is an EXPLAIN QUERY PLAN, a single
** record is added to the output to describe the table scan strategy in 
** pLevel.
*/
static void explainOneScan(
  Parse *pParse,                  /* Parse context */
  SrcList *pTabList,              /* Table list this loop refers to */
  WhereInfo *pWInfo,              /* WHERE clause this loop belongs to */
  int iLevel,                     /* Value for "level" column of output */

  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
){
#if !defined(SQLITE_DEBUG) && !defined(SQLITE_ENABLE_STMT_SCANSTATUS)
  if( pParse->explain==2 )
#endif
  {
    WhereLevel *pLevel = &pWInfo->a[iLevel];
    struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
    Vdbe *v = pParse->pVdbe;      /* VM being constructed */
    sqlite3 *db = pParse->db;     /* Database handle */
#ifdef SQLITE_OMIT_EXPLAIN
    int iId = 0;                  /* Select id (left-most output column) */
#else
    int iId = pParse->iSelectId;   /* Select id (left-most output column) */
#endif
    int isSearch;                 /* True for a SEARCH. False for SCAN. */
    WhereLoop *pLoop;             /* The controlling WhereLoop object */
    u32 flags;                    /* Flags that describe this loop */
    StrAccum str;                 /* EQP output string */
    char zBuf[100];               /* Initial space for EQP output string */
    const char *zObj;
    ExplainArg *pExplain;
    i64 nEstRow;                  /* Estimated rows per scan of pLevel */

    pLoop = pLevel->pWLoop;
    flags = pLoop->wsFlags;
    if( (flags&WHERE_MULTI_OR) ) return;

    sqlite3StrAccumInit(&str, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
    str.db = db;

    /* Reserve space at the start of the buffer managed by the StrAccum
    ** object for *pExplain.  */
    assert( sizeof(*pExplain)<=sizeof(zBuf) );

    /* Append the EQP text to the buffer */
    isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
            || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
            || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));
    sqlite3StrAccumAppendAll(&str, isSearch ? "SEARCH" : "SCAN");
    if( pItem->pSelect ){
#ifdef SQLITE_OMIT_EXPLAIN
      sqlite3XPrintf(&str, 0, " SUBQUERY 0");
#else
      sqlite3XPrintf(&str, 0, " SUBQUERY %d", pItem->iSelectId);
#endif
    }else{
      sqlite3XPrintf(&str, 0, " TABLE %s", pItem->zName);
    }

    if( pItem->zAlias ){
      sqlite3XPrintf(&str, 0, " AS %s", pItem->zAlias);
    }

        pExplain->iCsr = pLevel->iTabCur;
      }else{
        pExplain->iCsr = -1;
      }
      pExplain->nEst = nEstRow;
      pExplain->zName = (const char*)&pExplain[1];
      pExplain->zExplain = &pExplain->zName[sqlite3Strlen30(pExplain->zName)+1];
      pWInfo->iExplain = sqlite3VdbeAddOp4(v, OP_Explain, 
          iId, iLevel, pLevel->iFrom, (char*)pExplain,P4_EXPLAIN
      );
    }
  }
}
#else
# define explainOneScan(v,w,x,y,z)
#endif /* !SQLITE_OMIT_EXPLAIN || SQLITE_ENABLE_STMT_SCANSTATUS */


/*
** Generate code for the start of the iLevel-th loop in the WHERE clause
** implementation described by pWInfo.
*/
static Bitmask codeOneLoopStart(

        /* Loop through table entries that match term pOrTerm. */
        WHERETRACE(0xffff, ("Subplan for OR-clause:\n"));
        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
                                      wctrlFlags, iCovCur);
        assert( pSubWInfo || pParse->nErr || db->mallocFailed );
        if( pSubWInfo ){
          WhereLoop *pSubLoop;

          /* If an OP_Explain was added for this sub-loop, fix the P2 and
          ** P3 parameters to it so that they are relative to the current
          ** context.  */
          if( pSubWInfo->iExplain!=0 ){
            sqlite3VdbeChangeP2(v, pSubWInfo->iExplain, iLevel);
            sqlite3VdbeChangeP3(v, pSubWInfo->iExplain, pLevel->iFrom);
          }

          /* This is the sub-WHERE clause body.  First skip over
          ** duplicate rows from prior sub-WHERE clauses, and record the
          ** rowid (or PRIMARY KEY) for the current row so that the same
          ** row will be skipped in subsequent sub-WHERE clauses.
          */
          if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
            int r;

#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
      constructAutomaticIndex(pParse, &pWInfo->sWC,
                &pTabList->a[pLevel->iFrom], notReady, pLevel);
      if( db->mallocFailed ) goto whereBeginError;
    }
#endif
    explainOneScan(pParse, pTabList, pWInfo, ii, wctrlFlags);
    pLevel->addrBody = sqlite3VdbeCurrentAddr(v);
    notReady = codeOneLoopStart(pWInfo, ii, notReady);
    pWInfo->iContinue = pLevel->addrCont;
  }

  /* Done. */
  VdbeModuleComment((v, "Begin WHERE-core"));

  u8 okOnePass;             /* Ok to use one-pass algorithm for UPDATE/DELETE */
  u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
  u8 eDistinct;             /* One of the WHERE_DISTINCT_* values below */
  u8 nLevel;                /* Number of nested loop */
  int iTop;                 /* The very beginning of the WHERE loop */
  int iContinue;            /* Jump here to continue with next record */
  int iBreak;               /* Jump here to break out of the loop */
  int iExplain;             /* Address of OP_Explain (if WHERE_ONETABLE_ONLY) */
  int savedNQueryLoop;      /* pParse->nQueryLoop outside the WHERE loop */
  int aiCurOnePass[2];      /* OP_OpenWrite cursors for the ONEPASS opt */
  WhereMaskSet sMaskSet;    /* Map cursor numbers to bitmasks */
  WhereClause sWC;          /* Decomposition of the WHERE clause */
  WhereLevel a[1];          /* Information about each nest loop in WHERE */
};

  SELECT count(*) FROM t1, t2;
} 6
do_scanstatus_test 1.4 {
  nLoop 1 nVisit 2 nEst 2 zName t1 zExplain {SCAN TABLE t1}
  nLoop 2 nVisit 6 nEst 3 zName t2 zExplain {SCAN TABLE t2}
}

do_execsql_test 1.5 { ANALYZE }

do_execsql_test 1.6 {
  SELECT count(*) FROM t1, t2 WHERE t2.rowid>1;
} 4
do_scanstatus_test 1.7 {
  nLoop 1 nVisit 2 nEst 2 zName t2 zExplain 
  {SEARCH TABLE t2 USING INTEGER PRIMARY KEY (rowid>?)}
  nLoop 2 nVisit 4 nEst 2 zName t1 zExplain {SCAN TABLE t1}
}

do_execsql_test 1.8 {
  SELECT count(*) FROM t1, t2 WHERE t2.rowid>1;
} 4

do_scanstatus_test 1.9 {
  nLoop 2 nVisit 4 nEst 2 zName t2 zExplain 
  {SEARCH TABLE t2 USING INTEGER PRIMARY KEY (rowid>?)}
  nLoop 4 nVisit 8 nEst 2 zName t1 zExplain {SCAN TABLE t1}
}

do_test 1.9 {
  sqlite3_stmt_scanstatus_reset [db_last_stmt_ptr db]
} {}

do_scanstatus_test 1.10 {
  nLoop 0 nVisit 0 nEst 2 zName t2 zExplain 
  {SEARCH TABLE t2 USING INTEGER PRIMARY KEY (rowid>?)}
  nLoop 0 nVisit 0 nEst 2 zName t1 zExplain {SCAN TABLE t1}
}

#-------------------------------------------------------------------------
# Try a few different types of scans.
#
reset_db
do_execsql_test 2.1 {
  CREATE TABLE x1(i INTEGER PRIMARY KEY, j);
  INSERT INTO x1 VALUES(1, 'one');
  INSERT INTO x1 VALUES(2, 'two');
  INSERT INTO x1 VALUES(3, 'three');
  INSERT INTO x1 VALUES(4, 'four');
  CREATE INDEX x1j ON x1(j);

  SELECT * FROM x1 WHERE i=2;
} {2 two}

do_scanstatus_test 2.2 {
  nLoop 1 nVisit 1 nEst 1 zName x1 
  zExplain {SEARCH TABLE x1 USING INTEGER PRIMARY KEY (rowid=?)}
}

do_execsql_test 2.3.1 {
  SELECT * FROM x1 WHERE j='two'
} {2 two}
do_scanstatus_test 2.3.2 {
  nLoop 1 nVisit 1 nEst 10 zName x1j 
  zExplain {SEARCH TABLE x1 USING COVERING INDEX x1j (j=?)}
}

do_execsql_test 2.4.1 {
  SELECT * FROM x1 WHERE j<'two'
} {4 four 1 one 3 three}
do_scanstatus_test 2.4.2 {
  nLoop 1 nVisit 4 nEst 262144 zName x1j 
  zExplain {SEARCH TABLE x1 USING COVERING INDEX x1j (j<?)}
}

do_execsql_test 2.5.1 {
  SELECT * FROM x1 WHERE j>='two'
} {2 two}
do_scanstatus_test 2.5.2 {
  nLoop 1 nVisit 1 nEst 262144 zName x1j 
  zExplain {SEARCH TABLE x1 USING COVERING INDEX x1j (j>?)}
}

do_execsql_test 2.6.1 {
  SELECT * FROM x1 WHERE j BETWEEN 'three' AND 'two'
} {3 three 2 two}
do_scanstatus_test 2.6.2 {
  nLoop 1 nVisit 2 nEst 16384 zName x1j 
  zExplain {SEARCH TABLE x1 USING COVERING INDEX x1j (j>? AND j<?)}
}

do_execsql_test 2.7.1 {
  CREATE TABLE x2(i INTEGER, j, k);
  INSERT INTO x2 SELECT i, j, i || ' ' || j FROM x1;
  CREATE INDEX x2j ON x2(j);
  CREATE INDEX x2ij ON x2(i, j);
  SELECT * FROM x2 WHERE j BETWEEN 'three' AND 'two'
} {3 three {3 three} 2 two {2 two}}

do_scanstatus_test 2.7.2 {
  nLoop 1 nVisit 2 nEst 16384 zName x2j 
  zExplain {SEARCH TABLE x2 USING INDEX x2j (j>? AND j<?)}
}

do_execsql_test 2.8.1 {
  SELECT * FROM x2 WHERE i=1 AND j='two'
}
do_scanstatus_test 2.8.2 {
  nLoop 1 nVisit 1 nEst 8 zName x2ij 
  zExplain {SEARCH TABLE x2 USING INDEX x2ij (i=? AND j=?)}
}

do_execsql_test 2.9.1 {
  SELECT * FROM x2 WHERE i=5 AND j='two'
}
do_scanstatus_test 2.9.2 {
  nLoop 1 nVisit 0 nEst 8 zName x2ij 
  zExplain {SEARCH TABLE x2 USING INDEX x2ij (i=? AND j=?)}
}

do_execsql_test 2.10.1 {
  SELECT * FROM x2 WHERE i=3 AND j='three'
} {3 three {3 three}}
do_scanstatus_test 2.10.2 {
  nLoop 1 nVisit 2 nEst 8 zName x2ij 
  zExplain {SEARCH TABLE x2 USING INDEX x2ij (i=? AND j=?)}
}

#-------------------------------------------------------------------------
# Try with queries that use the OR optimization.
#
do_execsql_test 3.1 {
  CREATE TABLE a1(a, b, c, d);
  CREATE INDEX a1a ON a1(a);
  CREATE INDEX a1bc ON a1(b, c);

  WITH d(x) AS (SELECT 1 UNION ALL SELECT x+1 AS n FROM d WHERE n<=100)
  INSERT INTO a1 SELECT x, x, x, x FROM d;
}

do_execsql_test 3.2.1 {
  SELECT d FROM a1 WHERE (a=4 OR b=13)
} {4 13}

do_scanstatus_test 2.4 {
  nLoop 1 nVisit 2 nEst 10 zName a1a 
  zExplain {SEARCH TABLE a1 USING INDEX a1a (a=?)}

  nLoop 1 nVisit 2 nEst 10 zName a1bc 
  zExplain {SEARCH TABLE a1 USING INDEX a1bc (b=?)}
}



finish_test