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Overview
Comment:Fix comment typos in the where.c module. No code changes.
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SHA1: 1e0b77cf0edf3d26f76d83aa5466e9ec0e60a710
User & Date: drh 2013-08-30 17:50:35.740
Context
2013-08-30
19:59
Fix comment typo in analyze.c. No changes to code. (check-in: dbc3175044 user: mistachkin tags: trunk)
17:50
Fix comment typos in the where.c module. No code changes. (check-in: 1e0b77cf0e user: drh tags: trunk)
17:35
If the cost of two whereLoop objects is the same in every way except that one has fewer expected output rows than the other, then choose the one with fewer output rows. (check-in: 79e458ef7a user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/where.c.
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static int whereLoopResize(sqlite3*, WhereLoop*, int);

/*
** Each instance of this object holds a sequence of WhereLoop objects
** that implement some or all of a query plan.
**
** Think of each WhereLoop object as a node in a graph with arcs
** showing dependences and costs for travelling between nodes.  (That is
** not a completely accurate description because WhereLoop costs are a
** vector, not a scalar, and because dependences are many-to-one, not
** one-to-one as are graph nodes.  But it is a useful visualization aid.)
** Then a WherePath object is a path through the graph that visits some
** or all of the WhereLoop objects once.
**
** The "solver" works by creating the N best WherePath objects of length
** 1.  Then using those as a basis to compute the N best WherePath objects
** of length 2.  And so forth until the length of WherePaths equals the








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static int whereLoopResize(sqlite3*, WhereLoop*, int);

/*
** Each instance of this object holds a sequence of WhereLoop objects
** that implement some or all of a query plan.
**
** Think of each WhereLoop object as a node in a graph with arcs
** showing dependencies and costs for travelling between nodes.  (That is
** not a completely accurate description because WhereLoop costs are a
** vector, not a scalar, and because dependencies are many-to-one, not
** one-to-one as are graph nodes.  But it is a useful visualization aid.)
** Then a WherePath object is a path through the graph that visits some
** or all of the WhereLoop objects once.
**
** The "solver" works by creating the N best WherePath objects of length
** 1.  Then using those as a basis to compute the N best WherePath objects
** of length 2.  And so forth until the length of WherePaths equals the
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    if( (p->prereq & pTemplate->prereq)==p->prereq
     && p->rSetup<=pTemplate->rSetup
     && p->rRun<=pTemplate->rRun
     && p->nOut<=pTemplate->nOut
    ){
      /* This branch taken when p is equal or better than pTemplate in 
      ** all of (1) dependences (2) setup-cost, (3) run-cost, and
      ** (4) number of output rows. */
      assert( p->rSetup==pTemplate->rSetup );
      if( p->nLTerm<pTemplate->nLTerm
       && (p->wsFlags & WHERE_INDEXED)!=0
       && (pTemplate->wsFlags & WHERE_INDEXED)!=0
       && p->u.btree.pIndex==pTemplate->u.btree.pIndex
       && p->prereq==pTemplate->prereq








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    if( (p->prereq & pTemplate->prereq)==p->prereq
     && p->rSetup<=pTemplate->rSetup
     && p->rRun<=pTemplate->rRun
     && p->nOut<=pTemplate->nOut
    ){
      /* This branch taken when p is equal or better than pTemplate in 
      ** all of (1) dependencies (2) setup-cost, (3) run-cost, and
      ** (4) number of output rows. */
      assert( p->rSetup==pTemplate->rSetup );
      if( p->nLTerm<pTemplate->nLTerm
       && (p->wsFlags & WHERE_INDEXED)!=0
       && (pTemplate->wsFlags & WHERE_INDEXED)!=0
       && p->u.btree.pIndex==pTemplate->u.btree.pIndex
       && p->prereq==pTemplate->prereq
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    }
    if( (p->prereq & pTemplate->prereq)==pTemplate->prereq
     && p->rRun>=pTemplate->rRun
     && p->nOut>=pTemplate->nOut
     && ALWAYS(p->rSetup>=pTemplate->rSetup) /* See SETUP-INVARIANT above */
    ){
      /* Overwrite an existing WhereLoop with a better one: one that is
      ** better at one of (1) dependences, (2) setup-cost, (3) run-cost
      ** or (4) number of output rows, and is no worse in any of those
      ** categories. */
      pNext = p->pNextLoop;
      break;
    }
  }









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    }
    if( (p->prereq & pTemplate->prereq)==pTemplate->prereq
     && p->rRun>=pTemplate->rRun
     && p->nOut>=pTemplate->nOut
     && ALWAYS(p->rSetup>=pTemplate->rSetup) /* See SETUP-INVARIANT above */
    ){
      /* Overwrite an existing WhereLoop with a better one: one that is
      ** better at one of (1) dependencies, (2) setup-cost, (3) run-cost
      ** or (4) number of output rows, and is no worse in any of those
      ** categories. */
      pNext = p->pNextLoop;
      break;
    }
  }
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