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Optimize variable-size single row replacements #1039

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Merged
timsehn merged 1 commit into from
May 23, 2026
Merged

Optimize variable-size single row replacements #1039

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14 changes: 9 additions & 5 deletions src/prolly_mutate.c
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Original file line number Diff line number Diff line change
Expand Up @@ -663,13 +663,11 @@ static int tryInsertOrReplaceSingleNoRechunk(ProllyMutator *pMut){
const u8 *pOldVal;
int nOldVal;
ProllyNodeBuilder b;
int sameSize;
int i;

prollyNodeValue(pLeaf, idx, &pOldVal, &nOldVal);
if( nOldVal!=pEdit->nVal ){
prollyCursorClose(&cur);
return SQLITE_NOTFOUND;
}
sameSize = (nOldVal==pEdit->nVal);

prollyNodeBuilderInit(&b, 0, pMut->flags);
for(i=0; i<(int)pLeaf->nItems; i++){
Expand All @@ -685,7 +683,13 @@ static int tryInsertOrReplaceSingleNoRechunk(ProllyMutator *pMut){
return rc;
}
}
rc = writeBuilderNode(pMut->pStore, &b, &childHash);
if( sameSize ){
rc = writeBuilderNode(pMut->pStore, &b, &childHash);
}else{
rc = finishAndWriteBuilderNode(pMut->pStore, &b,
!cursorLeafIsRightmost(&cur),
&childHash);
}
prollyNodeBuilderFree(&b);
if( rc!=SQLITE_OK ){
prollyCursorClose(&cur);
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29 changes: 29 additions & 0 deletions test/invariant_test.c
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Expand Up @@ -959,6 +959,35 @@ static void test_single_row_mutation_fast_path(void){
check("single_mutation_integrity",
strcmp(queryScalarText(db, "PRAGMA integrity_check"), "ok")==0);

execSql(db, "CREATE TABLE tblob(id BLOB PRIMARY KEY, val TEXT, pad TEXT)");
execSql(db, "BEGIN");
for( i=1; i<=5000; i++ ){
char sql[256];
snprintf(sql, sizeof(sql),
"INSERT INTO tblob VALUES(x'%032x', 'row_%d', 'pad')", i, i);
execSql(db, sql);
}
execSql(db, "COMMIT");

execSql(db,
"UPDATE tblob SET val='short' WHERE id=x'000000000000000000000000000009c4'");
execSql(db,
"UPDATE tblob SET val='this replacement is intentionally longer' "
"WHERE id=x'00000000000000000000000000000d05'");

check("single_mutation_blob_count",
queryScalarInt(db, "SELECT count(*) FROM tblob")==5000);
check("single_mutation_blob_short",
strcmp(queryScalarText(db,
"SELECT val FROM tblob WHERE id=x'000000000000000000000000000009c4'"),
"short")==0);
check("single_mutation_blob_long",
strcmp(queryScalarText(db,
"SELECT val FROM tblob WHERE id=x'00000000000000000000000000000d05'"),
"this replacement is intentionally longer")==0);
check("single_mutation_blob_integrity",
strcmp(queryScalarText(db, "PRAGMA integrity_check"), "ok")==0);

sqlite3_close(db);
removeDb(dbpath);
}
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