Change the unions of the Table.addColOffset field from characters to bytes.

This makes the query that implements ALTER TABLE ADD COLUMN more complex and
slightly slower, but also makes CREATE TABLE statement parsing faster by
avoiding a call to sqlite3UtfCharLen().  Since, CREATE TABLE parsing is far
more common than ALTER TABLE, this is a net win for performance.

FossilOrigin-Name: 6f25f2529f1495a26129d7d407979906e4962b2de351f901d41cb037d05ba780

diff --git a/manifest b/manifest
index 1aca84feb22f344451d91761a5416b049aa1c67b..7ea3b257e62459863d1200b190e327144450af9a 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Use\sthe\scolumn\sname\shash\sto\simprove\sperformance\sof\scolumn\sname\scollision\ndetection\swhile\sparsing\sCREATE\sTABLE\sstatements.
-D 2021-01-01T19:17:01.346
+C Change\sthe\sunions\sof\sthe\sTable.addColOffset\sfield\sfrom\scharacters\sto\sbytes.\nThis\smakes\sthe\squery\sthat\simplements\sALTER\sTABLE\sADD\sCOLUMN\smore\scomplex\sand\nslightly\sslower,\sbut\salso\smakes\sCREATE\sTABLE\sstatement\sparsing\sfaster\sby\navoiding\sa\scall\sto\ssqlite3UtfCharLen().\s\sSince,\sCREATE\sTABLE\sparsing\sis\sfar\nmore\scommon\sthan\sALTER\sTABLE,\sthis\sis\sa\snet\swin\sfor\sperformance.
+D 2021-01-01T20:04:34.680
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -474,7 +474,7 @@ F spec.template 86a4a43b99ebb3e75e6b9a735d5fd293a24e90ca
 F sqlite.pc.in 42b7bf0d02e08b9e77734a47798d1a55a9e0716b
 F sqlite3.1 fc7ad8990fc8409983309bb80de8c811a7506786
 F sqlite3.pc.in 48fed132e7cb71ab676105d2a4dc77127d8c1f3a
-F src/alter.c b6de60d59419e34f5b48ff2b21fe0f9bb66fc714e5545a6ac790ac7a0c46548c
+F src/alter.c 36cae0d6e3e91a1996e1a472f8c7242c31a4e38ba4295e3056da198c04fd2a87
 F src/analyze.c 01c6c6765cb4d40b473b71d85535093730770bb186f2f473abac25f07fcdee5c
 F src/attach.c 0f497c15c4cfe3bdcb214f0dbdbbb6c5ed7e8a9308ac445c7959f5e5780437a9
 F src/auth.c 8d1df0e2ef8bafbedd4f1fe4baff03eb27507da4bf6e449df3613d383c4018b2
@@ -484,7 +484,7 @@ F src/btmutex.c 8acc2f464ee76324bf13310df5692a262b801808984c1b79defb2503bbafadb6
 F src/btree.c 0f9cb686871ae668817673f0823b55d1bcadbc86ea28bd22c590b064a8322d5a
 F src/btree.h 285f8377aa1353185a32bf455faafa9ff9a0d40d074d60509534d14990c7829e
 F src/btreeInt.h 7614cae30f95b6aed0c7cac7718276a55cfe2c77058cbfd8bef5b75329757331
-F src/build.c f5610708b09e6e2aed20e9f87e41abc9cb7d9c524b2af473b6b8f979185fcc3c
+F src/build.c 7a9983015d707482329820eb0ab6bc014554cbd89f8f0312e88ee47ca924257d
 F src/callback.c d0b853dd413255d2e337b34545e54d888ea02f20da5ad0e63585b389624c4a6c
 F src/complete.c a3634ab1e687055cd002e11b8f43eb75c17da23e
 F src/ctime.c 2a322b9a3d75771fb4d99e0702851f4f68dda982507a0f798eefb0712969a410
@@ -1895,7 +1895,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 5ac939e0adc923378173297e934c3664254a4fefbcddcc842bf4cc42dbaacf4f
-R 76ed3eb5d9ad1369259443b69c6d4eb4
+P d02820f03575e4633a7917427f11c19f99bd7b92f37d0ffe6fdc2418ad729813
+R d65e8365f48ba6717e932860e31b53aa
 U drh
-Z 392a8d945c1dcd1bc8026b48aa7097cf
+Z 862f00eca17b025046c1fc8e371a884b

diff --git a/manifest.uuid b/manifest.uuid
index 7ce76aea344091ade509ca76260810fb4c48115e..377d6e125da7344abb72da80bb61131bb89b8c34 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-d02820f03575e4633a7917427f11c19f99bd7b92f37d0ffe6fdc2418ad729813
\ No newline at end of file
+6f25f2529f1495a26129d7d407979906e4962b2de351f901d41cb037d05ba780
\ No newline at end of file

diff --git a/src/alter.c b/src/alter.c
index f4098863ddac8e2a3018655e21d497a90f37ed91..e0beb8f3edfc29d84e718f75066b034786bf9702 100644 (file)
--- a/src/alter.c
+++ b/src/alter.c
@@ -381,11 +381,14 @@ void sqlite3AlterFinishAddColumn(Parse *pParse, Token *pColDef){
       *zEnd-- = '\0';
     }
     db->mDbFlags |= DBFLAG_PreferBuiltin;
+    /* substr() operations on characters, but addColOffset is in bytes. So we
+    ** have to use printf() to translate between these units: */
     sqlite3NestedParse(pParse, 
         "UPDATE \"%w\"." DFLT_SCHEMA_TABLE " SET "
-          "sql = substr(sql,1,%d) || ', ' || %Q || substr(sql,%d) "
+          "sql = printf('%%.%ds, ',sql) || %Q"
+          " || substr(sql,1+length(printf('%%.%ds',sql))) "
         "WHERE type = 'table' AND name = %Q", 
-      zDb, pNew->addColOffset, zCol, pNew->addColOffset+1,
+      zDb, pNew->addColOffset, zCol, pNew->addColOffset,
       zTab
     );
     sqlite3DbFree(db, zCol);

diff --git a/src/build.c b/src/build.c
index 3a355304009850caa650d88ebaeab42e84023aa7..c9877951c6f41b2dc46d268a8abfbef1ba347788 100644 (file)
--- a/src/build.c
+++ b/src/build.c
@@ -2564,7 +2564,7 @@ void sqlite3EndTable(
         pCons = pEnd;
       }
       nName = (int)((const char *)pCons->z - zName);
-      p->addColOffset = 13 + sqlite3Utf8CharLen(zName, nName);
+      p->addColOffset = 13 + nName;
     }
 #endif
   }