Fix comments that were made obsolete by the removal of the column cache.

FossilOrigin-Name: 2041231d56c7b02b785015ef4d1af260d61326eab1b2a304c17faa3e33f76441

4 files changed, 2 insertions, 25 deletions

diff --git a/src/expr.c b/src/expr.c
index 889142d1e..271b065a3 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -3262,7 +3262,7 @@ int sqlite3ExprCodeGetColumn(
 
 /*
 ** Generate code to move content from registers iFrom...iFrom+nReg-1
-** over to iTo..iTo+nReg-1. Keep the column cache up-to-date.
+** over to iTo..iTo+nReg-1.
 */
 void sqlite3ExprCodeMove(Parse *pParse, int iFrom, int iTo, int nReg){
   assert( iFrom>=iTo+nReg || iFrom+nReg<=iTo );
@@ -5252,10 +5252,6 @@ int sqlite3GetTempReg(Parse *pParse){
 /*
 ** Deallocate a register, making available for reuse for some other
 ** purpose.
-**
-** If a register is currently being used by the column cache, then
-** the deallocation is deferred until the column cache line that uses
-** the register becomes stale.
 */
 void sqlite3ReleaseTempReg(Parse *pParse, int iReg){
   if( iReg && pParse->nTempReg<ArraySize(pParse->aTempReg) ){
diff --git a/src/select.c b/src/select.c
index c4ab18d2f..f97efa7a7 100644
--- a/src/select.c
+++ b/src/select.c
@@ -5334,17 +5334,6 @@ static void updateAccumulator(Parse *pParse, int regAcc, AggInfo *pAggInfo){
       sqlite3VdbeResolveLabel(v, addrNext);
     }
   }
-
-  /* Before populating the accumulator registers, clear the column cache.
-  ** Otherwise, if any of the required column values are already present 
-  ** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value
-  ** to pC->iMem. But by the time the value is used, the original register
-  ** may have been used, invalidating the underlying buffer holding the
-  ** text or blob value. See ticket [883034dcb5].
-  **
-  ** Another solution would be to change the OP_SCopy used to copy cached
-  ** values to an OP_Copy.
-  */
   if( regHit==0 && pAggInfo->nAccumulator ){
     regHit = regAcc;
   }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 1348d46f6..6304680ab 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1558,7 +1558,7 @@ struct sqlite3 {
 ** selectively disable various optimizations.
 */
 #define SQLITE_QueryFlattener 0x0001   /* Query flattening */
-#define SQLITE_ColumnCache    0x0002   /* Column cache */
+                          /*  0x0002   available for reuse */
 #define SQLITE_GroupByOrder   0x0004   /* GROUPBY cover of ORDERBY */
 #define SQLITE_FactorOutConst 0x0008   /* Constant factoring */
 #define SQLITE_DistinctOpt    0x0010   /* DISTINCT using indexes */
@@ -2958,13 +2958,6 @@ struct AutoincInfo {
 };
 
 /*
-** Size of the column cache
-*/
-#ifndef SQLITE_N_COLCACHE
-# define SQLITE_N_COLCACHE 10
-#endif
-
-/*
 ** At least one instance of the following structure is created for each
 ** trigger that may be fired while parsing an INSERT, UPDATE or DELETE
 ** statement. All such objects are stored in the linked list headed at
diff --git a/src/test1.c b/src/test1.c
index 9ffc2e2a8..93c71aa32 100644
--- a/src/test1.c
+++ b/src/test1.c
@@ -6982,7 +6982,6 @@ static int SQLITE_TCLAPI optimization_control(
     { "all",                 SQLITE_AllOpts        },
     { "none",                0                     },
     { "query-flattener",     SQLITE_QueryFlattener },
-    { "column-cache",        SQLITE_ColumnCache    },
     { "groupby-order",       SQLITE_GroupByOrder   },
     { "factor-constants",    SQLITE_FactorOutConst },
     { "distinct-opt",        SQLITE_DistinctOpt    },