From: drh <drh@noemail.net>
Date: Wed, 7 Nov 2018 16:46:43 +0000 (+0000)
Subject: Performance improvement in subroutine that decides whether or not a table
X-Git-Tag: version-3.26.0~47^2~3
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=e1857cc01564034ccf4a72a453f529795c8598d9;p=thirdparty%2Fsqlite.git

Performance improvement in subroutine that decides whether or not a table
is read-only.

FossilOrigin-Name: 6e4968b00507c4fdbe7e3c91f3f9cd61c6f1848092ddcf306f9fcb101a47fce7
---

diff --git a/manifest b/manifest
index 4ef71d9841..8fc9868f21 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Merge\sthe\sonefile\spermutation\sfix\sfrom\strunk.
-D 2018-11-07T16:12:34.740
+C Performance\simprovement\sin\ssubroutine\sthat\sdecides\swhether\sor\snot\sa\stable\nis\sread-only.
+D 2018-11-07T16:46:43.458
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F Makefile.in edbb6e20bb1decf65f6c64c9e61004a69bdf8afb39cdce5337c916b03dfcd1e3
@@ -455,7 +455,7 @@ F src/ctime.c 109e58d00f62e8e71ee1eb5944ac18b90171c928ab2e082e058056e1137cc20b
 F src/date.c ebe1dc7c8a347117bb02570f1a931c62dd78f4a2b1b516f4837d45b7d6426957
 F src/dbpage.c cfa87c8a9e3b5267a72faa3a592a497cd3810146c056c53a3472caf763c8556b
 F src/dbstat.c 9ad3f2d9d19a915d414870b9405b19493eed41975f3ad0d13f70fdd0831853b4
-F src/delete.c 36825ff2d6d4026f4cde42dd0642bfc8aeacc7596330d0159683d66cca715a1e
+F src/delete.c cec65c0e74be7492cafba1b77580732b0b1a41a4dbc4ac70909ac44b65b2a20b
 F src/expr.c 9aacc0b72348ba90010b672dcbbbe2fa56e1182043bc917a3a147b2bc57a5497
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 972a4ba14296bef2303a0abbad1e3d82bc3c61f9e6ce4e8e9528bdee68748812
@@ -1776,7 +1776,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 911e8a17a3810cd7042e91a32aba80dc3d6be88320c208e48f7bcee8b22a0ff2 13e21b7da8fe754e230b09ca0b9f1f69cd9aa20d4407ddd8b95ca3fb18c9abeb
-R 56bf1824a48b5de2380d01acb7d29fb0
+P e543bff87d1efc31a5b863085c056ce06c365cc7d9d3fef0ced7521bde536783
+R 72f25975d392eaabe6c843161e0c6c08
 U drh
-Z b5475e4e894f27e1fb706ff1a175ea2a
+Z 7e624fcbff194b9dd60db6c89a893b83
diff --git a/manifest.uuid b/manifest.uuid
index 531c357390..8181b428b9 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-e543bff87d1efc31a5b863085c056ce06c365cc7d9d3fef0ced7521bde536783
\ No newline at end of file
+6e4968b00507c4fdbe7e3c91f3f9cd61c6f1848092ddcf306f9fcb101a47fce7
\ No newline at end of file
diff --git a/src/delete.c b/src/delete.c
index 7007de375b..157e1a8de1 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -44,40 +44,47 @@ Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
   return pTab;
 }
 
+/* Return true if table pTab is read-only.
+**
+** A table is read-only if any of the following are true:
+**
+**   1) It is a virtual table and no implementation of the xUpdate method
+**      has been provided
+**
+**   2) It is a system table (i.e. sqlite_master), this call is not
+**      part of a nested parse and writable_schema pragma has not 
+**      been specified
+**
+**   3) The table is a shadow table, the database connection is in
+**      defensive mode, and the current sqlite3_prepare()
+**      is for a top-level SQL statement.
+*/
+static int tabIsReadOnly(Parse *pParse, Table *pTab){
+  sqlite3 *db;
+  if( IsVirtual(pTab) ){
+    return sqlite3GetVTable(pParse->db, pTab)->pMod->pModule->xUpdate==0;
+  }
+  if( (pTab->tabFlags & (TF_Readonly|TF_Shadow))==0 ) return 0;
+  db = pParse->db;
+  if( (pTab->tabFlags & TF_Readonly)!=0 ){
+    return sqlite3WritableSchema(db)==0 && pParse->nested==0;
+  }
+  assert( pTab->tabFlags & TF_Shadow );
+  return (db->flags & SQLITE_Defensive)!=0
+           && db->nVdbeExec==0
+           && db->pVtabCtx==0;
+}
+
 /*
 ** Check to make sure the given table is writable.  If it is not
 ** writable, generate an error message and return 1.  If it is
 ** writable return 0;
 */
 int sqlite3IsReadOnly(Parse *pParse, Table *pTab, int viewOk){
-  sqlite3 *db = pParse->db;
-  /* A table is not writable under the following circumstances:
-  **
-  **   1) It is a virtual table and no implementation of the xUpdate method
-  **      has been provided, or
-  **   2) It is a system table (i.e. sqlite_master), this call is not
-  **      part of a nested parse and writable_schema pragma has not 
-  **      been specified.
-  **   3) The table is a shadow table, the database connection is in
-  **      defensive mode, and the current sqlite3_prepare()
-  **      is for a top-level SQL statement.
-  **
-  ** In either case leave an error message in pParse and return non-zero.
-  */
-  if( ( IsVirtual(pTab) 
-     && sqlite3GetVTable(db, pTab)->pMod->pModule->xUpdate==0 )
-   || ( (pTab->tabFlags & TF_Readonly)!=0
-     && sqlite3WritableSchema(db)==0
-     && pParse->nested==0)
-   || ( (pTab->tabFlags & TF_Shadow)!=0
-     && (db->flags & SQLITE_Defensive)!=0
-     && db->nVdbeExec==0
-     && db->pVtabCtx==0)
-  ){
+  if( tabIsReadOnly(pParse, pTab) ){
     sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
     return 1;
   }
-
 #ifndef SQLITE_OMIT_VIEW
   if( !viewOk && pTab->pSelect ){
     sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);