The query planner tries to avoids using indexes that use unknown collating
functions.

FossilOrigin-Name: 02013fc120bf71a8be3550c696a588af8c92f2209f8e5db530624878ddc8aa7e
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 27b896d..47d9fc6 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2172,6 +2172,7 @@
   unsigned isCovering:1;   /* True if this is a covering index */
   unsigned noSkipScan:1;   /* Do not try to use skip-scan if true */
   unsigned hasStat1:1;     /* aiRowLogEst values come from sqlite_stat1 */
+  unsigned bNoQuery:1;     /* Do not use this index to optimize queries */
 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
   int nSample;             /* Number of elements in aSample[] */
   int nSampleCol;          /* Size of IndexSample.anEq[] and so on */
@@ -2984,7 +2985,7 @@
   int nMem;            /* Number of memory cells used so far */
   int nOpAlloc;        /* Number of slots allocated for Vdbe.aOp[] */
   int szOpAlloc;       /* Bytes of memory space allocated for Vdbe.aOp[] */
-  int iSelfTab;        /* Table for associated with an index on expr, or negative
+  int iSelfTab;        /* Table associated with an index on expr, or negative
                        ** of the base register during check-constraint eval */
   int iCacheLevel;     /* ColCache valid when aColCache[].iLevel<=iCacheLevel */
   int iCacheCnt;       /* Counter used to generate aColCache[].lru values */