diff --git a/ext/misc/zipfile.c b/ext/misc/zipfile.c
index 9f2258ef0b..e57dc38f30 100644
--- a/ext/misc/zipfile.c
+++ b/ext/misc/zipfile.c
@@ -1296,25 +1296,26 @@ static int zipfileBestIndex(
   sqlite3_index_info *pIdxInfo
 ){
   int i;
+  int idx = -1;
+  int unusable = 0;
 
   for(i=0; i<pIdxInfo->nConstraint; i++){
     const struct sqlite3_index_constraint *pCons = &pIdxInfo->aConstraint[i];
-    if( pCons->usable==0 ) continue;
-    if( pCons->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
     if( pCons->iColumn!=ZIPFILE_F_COLUMN_IDX ) continue;
-    break;
+    if( pCons->usable==0 ){
+      unusable = 1;
+    }else if( pCons->op==SQLITE_INDEX_CONSTRAINT_EQ ){
+      idx = i;
+    }
   }
-
-  if( i<pIdxInfo->nConstraint ){
-    pIdxInfo->aConstraintUsage[i].argvIndex = 1;
-    pIdxInfo->aConstraintUsage[i].omit = 1;
+  if( idx>=0 ){
+    pIdxInfo->aConstraintUsage[idx].argvIndex = 1;
+    pIdxInfo->aConstraintUsage[idx].omit = 1;
     pIdxInfo->estimatedCost = 1000.0;
     pIdxInfo->idxNum = 1;
-  }else{
-    pIdxInfo->estimatedCost = (double)(((sqlite3_int64)1) << 50);
-    pIdxInfo->idxNum = 0;
+  }else if( unusable ){
+    return SQLITE_CONSTRAINT;
   }
-
   return SQLITE_OK;
 }
 
diff --git a/manifest b/manifest
index 559a5ebd89..dc35326b83 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Update\sthe\sexplain\svirtual\stable\sto\smake\suse\sof\sSQLITE_CONSTRAINT.
-D 2018-11-16T19:19:58.887
+C Add\sSQLITE_CONSTRAINT\ssupport\sto\sthe\sxBestIndex\smethods\son\sdbstat,\nsqlite_dbpage,\sand\szipfile.
+D 2018-11-16T20:18:07.728
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in b730006b54c990461d864c5387f2e6f13aadb0236804555fb010ed6865a5f058
@@ -311,7 +311,7 @@ F ext/misc/vfsstat.c bf10ef0bc51e1ad6756629e1edb142f7a8db1178
 F ext/misc/vtablog.c 5538acd0c8ddaae372331bee11608d76973436b77d6a91e8635cfc9432fba5ae
 F ext/misc/vtshim.c 1976e6dd68dd0d64508c91a6dfab8e75f8aaf6cd
 F ext/misc/wholenumber.c 784b12543d60702ebdd47da936e278aa03076212
-F ext/misc/zipfile.c c4de8f0ad446ce4a49aae11ff7b771cd7af60d7136c0bcfb53da1475b9075e79
+F ext/misc/zipfile.c 1d731db326c40e11fc608f38132acff31619946c000e85ab8efe75bbedc2a441
 F ext/misc/zorder.c b0ff58fa643afa1d846786d51ea8d5c4b6b35aa0254ab5a82617db92f3adda64
 F ext/rbu/rbu.c 8681f6157db6adc82c34af24b14ea8a3be0146ad2a3b6c1d5da6cb8a5796c8ce
 F ext/rbu/rbu1.test 221d9c18a5e600ac9ac6b1810d99d9f99163a7909ba61597876ab6e4d4beb3d6
@@ -455,8 +455,8 @@ F src/callback.c 789bd33d188146f66c0dd8306472a72d1c05f71924b24a91caf6bd45cf9aba7
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 109e58d00f62e8e71ee1eb5944ac18b90171c928ab2e082e058056e1137cc20b
 F src/date.c ebe1dc7c8a347117bb02570f1a931c62dd78f4a2b1b516f4837d45b7d6426957
-F src/dbpage.c cfa87c8a9e3b5267a72faa3a592a497cd3810146c056c53a3472caf763c8556b
-F src/dbstat.c d54c2449d03f7d8a2e11a18f50364520ae1e364457fddb5e4dd79450bad428a0
+F src/dbpage.c 135eb3b5e74f9ef74bde5cec2571192c90c86984fa534c88bf4a055076fa19b7
+F src/dbstat.c 3c8bd4e77f0244fd2bd7cc90acf116ad2f8e82d70e536637f35ac2bc99b726f9
 F src/delete.c cec65c0e74be7492cafba1b77580732b0b1a41a4dbc4ac70909ac44b65b2a20b
 F src/expr.c 9aacc0b72348ba90010b672dcbbbe2fa56e1182043bc917a3a147b2bc57a5497
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
@@ -1778,7 +1778,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 3f34f4f561c77f8ec88906818f2984dcf8f17d1645bac175e9027595517560bc
-R bb2adeaa580d1c642edf2f21d75f48f2
+P b2d41ff7027b44ccb5dffc303c47d42f1f6fd66ce22e90450d3a666c73fe8b8e
+R 89e023a4c43db2de4dccc99f272c82a3
 U drh
-Z f6b6b46a521f0bb21911f77fd6557c2e
+Z 840051de1c80831f334c3f2a45d8f7da
diff --git a/manifest.uuid b/manifest.uuid
index fa71cc2fab..79e644ca51 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-b2d41ff7027b44ccb5dffc303c47d42f1f6fd66ce22e90450d3a666c73fe8b8e
\ No newline at end of file
+5cd24e552b4fed71cfb2e37929371175682f23f1430df2900a87e6a5823d138e
\ No newline at end of file
diff --git a/src/dbpage.c b/src/dbpage.c
index 4f46659018..27c962d144 100644
--- a/src/dbpage.c
+++ b/src/dbpage.c
@@ -119,9 +119,8 @@ static int dbpageBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
     if( p->iColumn!=DBPAGE_COLUMN_SCHEMA ) continue;
     if( p->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
     if( !p->usable ){
-      /* No solution.  Use the default SQLITE_BIG_DBL cost */
-      pIdxInfo->estimatedRows = 0x7fffffff;
-      return SQLITE_OK;
+      /* No solution. */
+      return SQLITE_CONSTRAINT;
     }
     iPlan = 2;
     pIdxInfo->aConstraintUsage[i].argvIndex = 1;
diff --git a/src/dbstat.c b/src/dbstat.c
index e49ace11f3..a6e521bee0 100644
--- a/src/dbstat.c
+++ b/src/dbstat.c
@@ -194,17 +194,15 @@ static int statDisconnect(sqlite3_vtab *pVtab){
 static int statBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
   int i;
 
-  pIdxInfo->estimatedCost = 1.0e6;  /* Initial cost estimate */
-
   /* Look for a valid schema=? constraint.  If found, change the idxNum to
   ** 1 and request the value of that constraint be sent to xFilter.  And
   ** lower the cost estimate to encourage the constrained version to be
   ** used.
   */
   for(i=0; i<pIdxInfo->nConstraint; i++){
-    if( pIdxInfo->aConstraint[i].usable==0 ) continue;
-    if( pIdxInfo->aConstraint[i].op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
     if( pIdxInfo->aConstraint[i].iColumn!=10 ) continue;
+    if( pIdxInfo->aConstraint[i].usable==0 ) return SQLITE_CONSTRAINT;
+    if( pIdxInfo->aConstraint[i].op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
     pIdxInfo->idxNum = 1;
     pIdxInfo->estimatedCost = 1.0;
     pIdxInfo->aConstraintUsage[i].argvIndex = 1;