Add SQLITE_STMTSTATUS_FILTER_HIT and _MISS for tracking the effectiveness

of Bloom filters.

FossilOrigin-Name: 24ba535d200fc8a99dd8e66c6d100b5f6ae442098bafb152008429398eefe3e7

4 files changed, 19 insertions, 1 deletions

diff --git a/src/shell.c.in b/src/shell.c.in
index 543141c9e..c46eaffd6 100644
--- a/src/shell.c.in
+++ b/src/shell.c.in
@@ -2790,6 +2790,7 @@ static int display_stats(
   }
 
   if( pArg->pStmt ){
+    int iHit, iMiss;
     iCur = sqlite3_stmt_status(pArg->pStmt, SQLITE_STMTSTATUS_FULLSCAN_STEP,
                                bReset);
     raw_printf(pArg->out, "Fullscan Steps:                      %d\n", iCur);
@@ -2797,6 +2798,12 @@ static int display_stats(
     raw_printf(pArg->out, "Sort Operations:                     %d\n", iCur);
     iCur = sqlite3_stmt_status(pArg->pStmt, SQLITE_STMTSTATUS_AUTOINDEX,bReset);
     raw_printf(pArg->out, "Autoindex Inserts:                   %d\n", iCur);
+    iHit = sqlite3_stmt_status(pArg->pStmt, SQLITE_STMTSTATUS_FILTER_HIT, bReset);
+    iMiss = sqlite3_stmt_status(pArg->pStmt, SQLITE_STMTSTATUS_FILTER_MISS, bReset);
+    if( iHit || iMiss ){
+      raw_printf(pArg->out, "Bloom filter bypass taken:           %d/%d\n",
+            iHit, iHit+iMiss);
+    }
     iCur = sqlite3_stmt_status(pArg->pStmt, SQLITE_STMTSTATUS_VM_STEP, bReset);
     raw_printf(pArg->out, "Virtual Machine Steps:               %d\n", iCur);
     iCur = sqlite3_stmt_status(pArg->pStmt, SQLITE_STMTSTATUS_REPREPARE,bReset);
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 98a028b0b..4125122e1 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -8467,6 +8467,13 @@ int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
 ** The counter is incremented on the first [sqlite3_step()] call of each
 ** cycle.
 **
+** [[SQLITE_STMTSTATUS_FILTER HIT]] <dt>SQLITE_STMTSTATUS_FILTER_HIT</dt>
+** <dd>^This is the number of times that a join step was bypassed because
+** a Bloom filtered returned non-found.  The corresponding
+** SQLITE_STMTSTATUS_FILTER_MISS value is the number of times that the
+** Bloom filter returned a find, and thus the join step had to be processed
+** as normal.
+**
 ** [[SQLITE_STMTSTATUS_MEMUSED]] <dt>SQLITE_STMTSTATUS_MEMUSED</dt>
 ** <dd>^This is the approximate number of bytes of heap memory
 ** used to store the prepared statement.  ^This value is not actually
@@ -8481,6 +8488,8 @@ int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);
 #define SQLITE_STMTSTATUS_VM_STEP           4
 #define SQLITE_STMTSTATUS_REPREPARE         5
 #define SQLITE_STMTSTATUS_RUN               6
+#define SQLITE_STMTSTATUS_FILTER_MISS       7
+#define SQLITE_STMTSTATUS_FILTER_HIT        8
 #define SQLITE_STMTSTATUS_MEMUSED           99
 
 /*
diff --git a/src/vdbe.c b/src/vdbe.c
index c2281e70a..0abe64a71 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -8239,8 +8239,10 @@ case OP_Filter: {          /* jump */
   h %= pIn1->n;
   if( (pIn1->z[h/8] & (1<<(h&7)))==0 ){
     VdbeBranchTaken(1, 2);
+    p->aCounter[SQLITE_STMTSTATUS_FILTER_HIT]++;
     goto jump_to_p2;
   }else{
+    p->aCounter[SQLITE_STMTSTATUS_FILTER_MISS]++;
     VdbeBranchTaken(0, 2);
   }
   break;
diff --git a/src/vdbeInt.h b/src/vdbeInt.h
index c76cdbfdb..38863f6d6 100644
--- a/src/vdbeInt.h
+++ b/src/vdbeInt.h
@@ -430,7 +430,7 @@ struct Vdbe {
   bft bIsReader:1;        /* True for statements that read */
   yDbMask btreeMask;      /* Bitmask of db->aDb[] entries referenced */
   yDbMask lockMask;       /* Subset of btreeMask that requires a lock */
-  u32 aCounter[7];        /* Counters used by sqlite3_stmt_status() */
+  u32 aCounter[9];        /* Counters used by sqlite3_stmt_status() */
   char *zSql;             /* Text of the SQL statement that generated this */
 #ifdef SQLITE_ENABLE_NORMALIZE
   char *zNormSql;         /* Normalization of the associated SQL statement */