Add code to maintain indexes with expression arguments across DELETE, INSERT,

and UPDATE statements.  Legacy tests pass, but the new code paths are still
largely untested.  The query planner currently makes no effort to use
expression indexes.

FossilOrigin-Name: efaabdb71626bdc03768e87e186c72f6f3da75b2

1 files changed, 42 insertions, 18 deletions

diff --git a/src/build.c b/src/build.c
index 64bfe1b06..fc50fdd82 100644
--- a/src/build.c
+++ b/src/build.c
@@ -443,6 +443,7 @@ static void freeIndex(sqlite3 *db, Index *p){
   sqlite3DeleteIndexSamples(db, p);
 #endif
   sqlite3ExprDelete(db, p->pPartIdxWhere);
+  sqlite3ExprListDelete(db, p->aColExpr);
   sqlite3DbFree(db, p->zColAff);
   if( p->isResized ) sqlite3DbFree(db, p->azColl);
 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
@@ -3101,32 +3102,47 @@ Index *sqlite3CreateIndex(
     sortOrderMask = 0;    /* Ignore DESC */
   }
 
-  /* Scan the names of the columns of the table to be indexed and
-  ** load the column indices into the Index structure.  Report an error
-  ** if any column is not found.
+  /* Analyze the list of expressions that form the terms of the index and
+  ** report any errors.  In the common case where the expression is exactly
+  ** a table column, store that column in aiColumn[].  For general expressions,
+  ** populate pIndex->aColExpr and store -2 in aiColumn[].
   **
-  ** TODO:  Add a test to make sure that the same column is not named
-  ** more than once within the same index.  Only the first instance of
-  ** the column will ever be used by the optimizer.  Note that using the
-  ** same column more than once cannot be an error because that would 
-  ** break backwards compatibility - it needs to be a warning.
+  ** TODO: Issue a warning if two or more columns of the index are identical.
+  ** TODO: Issue a warning if the table primary key is used as part of the
+  ** index key.
   */
   for(i=0, pListItem=pList->a; i<pList->nExpr; i++, pListItem++){
-    Expr *pCExpr;
-    int requestedSortOrder;
+    Expr *pCExpr;                  /* The i-th index expression */
+    int requestedSortOrder;        /* ASC or DESC on the i-th expression */
     char *zColl;                   /* Collation sequence name */
 
     sqlite3ResolveSelfReference(pParse, pTab, NC_IdxExpr, pListItem->pExpr, 0);
     if( pParse->nErr ) goto exit_create_index;
     pCExpr = sqlite3ExprSkipCollate(pListItem->pExpr);
     if( pCExpr->op!=TK_COLUMN ){
-      sqlite3ErrorMsg(pParse, "indexes on expressions not yet supported");
-      continue;
+      if( pTab==pParse->pNewTable ){
+        sqlite3ErrorMsg(pParse, "expressions prohibited in PRIMARY KEY and "
+                                "UNIQUE constraints");
+        goto exit_create_index;
+      }
+      if( pIndex->aColExpr==0 ){
+        pIndex->aColExpr = sqlite3ExprListDup(db, pList, 0);
+      }
+      j = -2;
+      pIndex->aiColumn[i] = -2;
+      if( sqlite3ExprCanBeNull(pList->a[i].pExpr) ){
+        pIndex->uniqNotNull = 1;
+      }
+    }else{
+      j = pCExpr->iColumn;
+      assert( j<=0x7fff );
+      if( j<0 ){
+        j = pTab->iPKey;
+      }else if( pTab->aCol[j].notNull==0 ){
+        pIndex->uniqNotNull = 0;
+      }
+      pIndex->aiColumn[i] = (i16)j;
     }
-    j = pCExpr->iColumn;
-    assert( j<=0x7fff );
-    if( j<0 ) j = pTab->iPKey;
-    pIndex->aiColumn[i] = (i16)j;
     zColl = 0;
     if( pListItem->pExpr->op==TK_COLLATE ){
       int nColl;
@@ -3147,11 +3163,16 @@ Index *sqlite3CreateIndex(
     pIndex->azColl[i] = zColl;
     requestedSortOrder = pListItem->sortOrder & sortOrderMask;
     pIndex->aSortOrder[i] = (u8)requestedSortOrder;
-    if( pTab->aCol[j].notNull==0 ) pIndex->uniqNotNull = 0;
   }
+
+  /* Append the table key to the end of the index.  For WITHOUT ROWID
+  ** tables (when pPk!=0) this will be the declared PRIMARY KEY.  For
+  ** normal tables (when pPk==0) this will be the rowid.
+  */
   if( pPk ){
     for(j=0; j<pPk->nKeyCol; j++){
       int x = pPk->aiColumn[j];
+      assert( x>=0 );
       if( hasColumn(pIndex->aiColumn, pIndex->nKeyCol, x) ){
         pIndex->nColumn--; 
       }else{
@@ -3202,6 +3223,7 @@ Index *sqlite3CreateIndex(
       for(k=0; k<pIdx->nKeyCol; k++){
         const char *z1;
         const char *z2;
+        assert( pIdx->aiColumn[k]>=0 );
         if( pIdx->aiColumn[k]!=pIndex->aiColumn[k] ) break;
         z1 = pIdx->azColl[k];
         z2 = pIndex->azColl[k];
@@ -4093,7 +4115,9 @@ void sqlite3UniqueConstraint(
 
   sqlite3StrAccumInit(&errMsg, pParse->db, 0, 0, 200);
   for(j=0; j<pIdx->nKeyCol; j++){
-    char *zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
+    char *zCol;
+    assert( pIdx->aiColumn[j]>=0 );
+    zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
     if( j ) sqlite3StrAccumAppend(&errMsg, ", ", 2);
     sqlite3StrAccumAppendAll(&errMsg, pTab->zName);
     sqlite3StrAccumAppend(&errMsg, ".", 1);