SQLite

** expressions are completely identical.  Return 1 if they differ only
** by a COLLATE operator at the top level.  Return 2 if there are differences
** other than the top-level COLLATE operator.
**
** If any subelement of pB has Expr.iTable==(-1) then it is allowed
** to compare equal to an equivalent element in pA with Expr.iTable==iTab.
**
** The pA side might be using TK_REGISTER.  If that is the case and pB is
** not using TK_REGISTER but is otherwise equivalent, then still return 0.
**
** Sometimes this routine will return 2 even if the two expressions
** really are equivalent.  If we cannot prove that the expressions are
** identical, we return 2 just to be safe.  So if this routine
** returns 2, then you do not really know for certain if the two
** expressions are the same.  But if you get a 0 or 1 return, then you
** can be sure the expressions are the same.  In the places where
** this routine is used, it does not hurt to get an extra 2 - that
** just might result in some slightly slower code.  But returning
** an incorrect 0 or 1 could lead to a malfunction.
*/
int sqlite3ExprCompare(Expr *pA, Expr *pB, int iTab){
  if( pA==0||pB==0 ){
    return pB==pA ? 0 : 2;
  }
  assert( !ExprHasAnyProperty(pA, EP_TokenOnly|EP_Reduced) );
  assert( !ExprHasAnyProperty(pB, EP_TokenOnly|EP_Reduced) );
  if( ExprHasProperty(pA, EP_xIsSelect) || ExprHasProperty(pB, EP_xIsSelect) ){
    return 2;
  }
  if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 2;
  if( pA->op!=pB->op && (pA->op!=TK_REGISTER || pA->op2!=pB->op) ){
    if( pA->op==TK_COLLATE && sqlite3ExprCompare(pA->pLeft, pB, iTab)<2 ){
      return 1;
    }
    if( pB->op==TK_COLLATE && sqlite3ExprCompare(pA, pB->pLeft, iTab)<2 ){
      return 1;
    }
    return 2;
  }
  if( sqlite3ExprCompare(pA->pLeft, pB->pLeft, iTab) ) return 2;
  if( sqlite3ExprCompare(pA->pRight, pB->pRight, iTab) ) return 2;
  if( sqlite3ExprListCompare(pA->x.pList, pB->x.pList, iTab) ) return 2;
  if( pA->iColumn!=pB->iColumn ) return 2;
  if( pA->iTable!=pB->iTable 
   && pA->op!=TK_REGISTER
   && (pA->iTable!=iTab || pB->iTable>=0) ) return 2;
  if( ExprHasProperty(pA, EP_IntValue) ){
    if( !ExprHasProperty(pB, EP_IntValue) || pA->u.iValue!=pB->u.iValue ){
      return 2;
    }
  }else if( pA->op!=TK_COLUMN && ALWAYS(pA->op!=TK_AGG_COLUMN) && pA->u.zToken){
    if( ExprHasProperty(pB, EP_IntValue) || NEVER(pB->u.zToken==0) ) return 2;
    if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){

        for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
          sqlite3VdbeAddOp2(v, OP_Integer, pIdx->tnum, 2+cnt);
          cnt++;
        }
      }

      /* Make sure sufficient number of registers have been allocated */
      pParse->nMem = MAX( pParse->nMem, cnt+7 );

      /* Do the b-tree integrity checks */
      sqlite3VdbeAddOp3(v, OP_IntegrityCk, 2, cnt, 1);
      sqlite3VdbeChangeP5(v, (u8)i);
      addr = sqlite3VdbeAddOp1(v, OP_IsNull, 2);
      sqlite3VdbeAddOp4(v, OP_String8, 0, 3, 0,
         sqlite3MPrintf(db, "*** in database %s ***\n", db->aDb[i].zName),

        Index *pIdx;
        int loopTop;

        if( pTab->pIndex==0 ) continue;
        addr = sqlite3VdbeAddOp1(v, OP_IfPos, 1);  /* Stop if out of errors */
        sqlite3VdbeAddOp2(v, OP_Halt, 0, 0);
        sqlite3VdbeJumpHere(v, addr);
        sqlite3ExprCacheClear(pParse);
        sqlite3OpenTableAndIndices(pParse, pTab, 1, OP_OpenRead);
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
          sqlite3VdbeAddOp2(v, OP_Integer, 0, 7+j); /* index entries counter */
        }
        pParse->nMem = MAX(pParse->nMem, 7+j);
        loopTop = sqlite3VdbeAddOp2(v, OP_Rewind, 1, 0) + 1;
        for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){

    pLoop->aLTerm[0] = pTerm;
    pLoop->nLTerm = 1;
    pLoop->u.btree.nEq = 1;
    /* TUNING: Cost of a rowid lookup is 10 */
    pLoop->rRun = 33;  /* 33==whereCost(10) */
  }else{
    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
      if( pIdx->onError==OE_None || pIdx->pPartIdxWhere!=0 ) continue;
      for(j=0; j<pIdx->nColumn; j++){
        pTerm = findTerm(pWC, iCur, pIdx->aiColumn[j], 0, WO_EQ, pIdx);
        if( pTerm==0 ) break;
        whereLoopResize(pWInfo->pParse->db, pLoop, j);
        pLoop->aLTerm[j] = pTerm;
      }
      if( j!=pIdx->nColumn ) continue;

set testdir [file dirname $argv0]
source $testdir/tester.tcl

load_static_extension db wholenumber;
do_test index6-1.1 {
  # Able to parse and manage partial indices
  execsql {
    CREATE TABLE t1(a,b,c);
    CREATE INDEX t1a ON t1(a) WHERE a IS NOT NULL;
    CREATE INDEX t1b ON t1(b) WHERE b>10;
    CREATE VIRTUAL TABLE nums USING wholenumber;
    INSERT INTO t1(a,b,c)
       SELECT CASE WHEN value%3!=0 THEN value END, value, value
         FROM nums WHERE value<=20;
    SELECT count(a), count(b) FROM t1;
    PRAGMA integrity_check;
  }
} {14 20 ok}

# Error conditions during parsing...
#
do_test index6-1.2 {
  catchsql {
    CREATE INDEX bad1 ON t1(a,b) WHERE x IS NOT NULL;
  }
} {1 {no such column: x}}
do_test index6-1.3 {
  catchsql {

  execsql {
    ANALYZE;
    SELECT idx, stat FROM sqlite_stat1 ORDER BY idx;
    PRAGMA integrity_check;
  }
} {{} 20 t1a {14 1} t1b {10 1} ok}

# STAT1 shows the partial indices have a reduced number of
# rows.
#
do_test index6-1.11 {
  execsql {
    UPDATE t1 SET a=b;
    ANALYZE;
    SELECT idx, stat FROM sqlite_stat1 ORDER BY idx;
    PRAGMA integrity_check;
  }

  execsql {
    CREATE INDEX t1c ON t1(c);
    ANALYZE;
    SELECT idx, stat FROM sqlite_stat1 ORDER BY idx;
    PRAGMA integrity_check;
  }
} {t1a {10 1} t1b {8 1} t1c {15 1} ok}

# Queries use partial indices as appropriate times.
#
do_test index6-2.1 {
  execsql {
    CREATE TABLE t2(a,b);
    INSERT INTO t2(a,b) SELECT value, value FROM nums WHERE value<1000;
    UPDATE t2 SET a=NULL WHERE b%5==0;
    CREATE INDEX t2a1 ON t2(a) WHERE a IS NOT NULL;
    SELECT count(*) FROM t2 WHERE a IS NOT NULL;
  }
} {800}
do_test index6-2.2 {
  execsql {
    EXPLAIN QUERY PLAN
    SELECT * FROM t2 WHERE a=5;
  }
} {/.* TABLE t2 USING INDEX t2a1 .*/}
do_test index6-2.3 {
  execsql {
    EXPLAIN QUERY PLAN
    SELECT * FROM t2 WHERE a IS NOT NULL;
  }
} {/.* TABLE t2 USING INDEX t2a1 .*/}
do_test index6-2.4 {
  execsql {
    EXPLAIN QUERY PLAN
    SELECT * FROM t2 WHERE a IS NULL;
  }
} {~/.*INDEX t2a1.*/}

do_execsql_test index6-2.101 {
  DROP INDEX t2a1;
  UPDATE t2 SET a=b, b=b+10000;
  SELECT b FROM t2 WHERE a=15;
} {10015}
do_execsql_test index6-2.102 {
  CREATE INDEX t2a2 ON t2(a) WHERE a<100 OR a>200;
  SELECT b FROM t2 WHERE a=15;
  PRAGMA integrity_check;
} {10015 ok}
do_execsql_test index6-2.102eqp {
  EXPLAIN QUERY PLAN
  SELECT b FROM t2 WHERE a=15;
} {~/.*INDEX t2a2.*/}
do_execsql_test index6-2.103 {
  SELECT b FROM t2 WHERE a=15 AND a<100;
} {10015}
do_execsql_test index6-2.103eqp {
  EXPLAIN QUERY PLAN
  SELECT b FROM t2 WHERE a=15 AND a<100;
} {/.*INDEX t2a2.*/}
do_execsql_test index6-2.104 {
  SELECT b FROM t2 WHERE a=515 AND a>200;
} {10515}
do_execsql_test index6-2.104eqp {
  EXPLAIN QUERY PLAN
  SELECT b FROM t2 WHERE a=515 AND a>200;
} {/.*INDEX t2a2.*/}

# Partial UNIQUE indices
#
do_execsql_test index6-3.1 {
  CREATE TABLE t3(a,b);
  INSERT INTO t3 SELECT value, value FROM nums WHERE value<200;
  UPDATE t3 SET a=999 WHERE b%5!=0;
  CREATE UNIQUE INDEX t3a ON t3(a) WHERE a<>999;
} {}
do_test index6-3.2 {
  # unable to insert a duplicate row a-value that is not 999.
  catchsql {
    INSERT INTO t3(a,b) VALUES(150, 'test1');
  }
} {1 {column a is not unique}}
do_test index6-3.3 {
  # can insert multiple rows with a==999 because such rows are not
  # part of the unique index.
  catchsql {
    INSERT INTO t3(a,b) VALUES(999, 'test1'), (999, 'test2');
  }
} {0 {}}
do_execsql_test index6-3.4 {
  SELECT count(*) FROM t3 WHERE a=999;
} {162}
integrity_check index6-3.5

finish_test