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

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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
This commit is contained in:
drh 2021-01-01 20:04:34 +00:00
parent 3e992d1ab7
commit 37114fbfcc
4 changed files with 14 additions and 11 deletions
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14
manifest
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@ -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

2
manifest.uuid
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@ -1 +1 @@
d02820f03575e4633a7917427f11c19f99bd7b92f37d0ffe6fdc2418ad729813
6f25f2529f1495a26129d7d407979906e4962b2de351f901d41cb037d05ba780

7
src/alter.c
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@ -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);

2
src/build.c
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@ -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
}