Add experimental "costmult" logic. Only enabled when compiled with

-DSQLITE_ENABLE_COSTMULT.

FossilOrigin-Name: 729ece40885ed7f52c5981364833fc62281a388b

src/analyze.c

@@ -1432,10 +1432,13 @@ static void decodeIntArray(
     if( sqlite3_strglob("unordered*", z)==0 ){
       pIndex->bUnordered = 1;
     }else if( sqlite3_strglob("sz=[0-9]*", z)==0 ){
-      int v32 = 0;
-      sqlite3GetInt32(z+3, &v32);
-      pIndex->szIdxRow = sqlite3LogEst(v32);
+      pIndex->szIdxRow = sqlite3LogEst(sqlite3Atoi(z+3));
     }
+#ifdef SQLITE_ENABLE_COSTMULT
+    else if( sqlite3_strglob("costmult=[0-9]*",z)==0 ){
+      pIndex->pTable->costMult = sqlite3LogEst(sqlite3Atoi(z+9));
+    }
+#endif
     while( z[0]!=0 && z[0]!=' ' ) z++;
     while( z[0]==' ' ) z++;
   }
@@ -1484,6 +1487,9 @@ static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
   }else{
     Index fakeIdx;
     fakeIdx.szIdxRow = pTable->szTabRow;
+#ifdef SQLITE_ENABLE_COSTMULT
+    fakeIdx.pTable = pTable;
+#endif
     decodeIntArray((char*)z, 1, 0, &pTable->nRowLogEst, &fakeIdx);
     pTable->szTabRow = fakeIdx.szIdxRow;
   }

src/sqliteInt.h

@@ -1477,6 +1477,9 @@ struct Table {
   i16 nCol;            /* Number of columns in this table */
   u16 nRef;            /* Number of pointers to this Table */
   LogEst szTabRow;     /* Estimated size of each table row in bytes */
+#ifdef SQLITE_ENABLE_COSTMULT
+  LogEst costMult;     /* Cost multiplier for using this table */
+#endif
   u8 tabFlags;         /* Mask of TF_* values */
   u8 keyConf;          /* What to do in case of uniqueness conflict on iPKey */
 #ifndef SQLITE_OMIT_ALTERTABLE

src/where.c

@@ -4230,6 +4230,16 @@ static void whereLoopOutputAdjust(WhereClause *pWC, WhereLoop *pLoop){
   }
 }
 
+/*
+** Adjust the cost C by the costMult facter T.  This only occurs if
+** compiled with -DSQLITE_ENABLE_COSTMULT
+*/
+#ifdef SQLITE_ENABLE_COSTMULT
+# define ApplyCostMultiplier(C,T)  C += T
+#else
+# define ApplyCostMultiplier(C,T)
+#endif
+
 /*
 ** We have so far matched pBuilder->pNew->u.btree.nEq terms of the 
 ** index pIndex. Try to match one more.
@@ -4457,6 +4467,7 @@ static int whereLoopAddBtreeIndex(
     if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
       pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut + 16);
     }
+    ApplyCostMultiplier(pNew->rRun, pProbe->pTable->costMult);
 
     nOutUnadjusted = pNew->nOut;
     pNew->rRun += nInMul + nIn;
@@ -4671,6 +4682,7 @@ static int whereLoopAddBtree(
         ** approximately 7*N*log2(N) where N is the number of rows in
         ** the table being indexed. */
         pNew->rSetup = rLogSize + rSize + 28;  assert( 28==sqlite3LogEst(7) );
+        ApplyCostMultiplier(pNew->rSetup, pTab->costMult);
         /* TUNING: Each index lookup yields 20 rows in the table.  This
         ** is more than the usual guess of 10 rows, since we have no way
         ** of knowning how selective the index will ultimately be.  It would
@@ -4712,6 +4724,7 @@ static int whereLoopAddBtree(
       pNew->iSortIdx = b ? iSortIdx : 0;
       /* TUNING: Cost of full table scan is (N*3.0). */
       pNew->rRun = rSize + 16;
+      ApplyCostMultiplier(pNew->rRun, pTab->costMult);
       whereLoopOutputAdjust(pWC, pNew);
       rc = whereLoopInsert(pBuilder, pNew);
       pNew->nOut = rSize;
@@ -4747,7 +4760,7 @@ static int whereLoopAddBtree(
         if( m!=0 ){
           pNew->rRun = sqlite3LogEstAdd(pNew->rRun, rSize+16);
         }
-
+        ApplyCostMultiplier(pNew->rRun, pTab->costMult);
         whereLoopOutputAdjust(pWC, pNew);
         rc = whereLoopInsert(pBuilder, pNew);
         pNew->nOut = rSize;