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Optimize sqlite3.oo1.DB.exec() for the rowMode='object' case to avoid converting the object property keys (column names) from native code to JS for each row. This speeds up large data sets considerably and addresses the report in [forum:3632183d2470617d|forum post 3632183d2470617d].

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FossilOrigin-Name: 8b41ef8690001eb299f5b7182c28f5318333bff5b505e1d59d6e6f4556b1c759
This commit is contained in:
stephan
2024-04-04 22:53:09 +00:00
parent f895173c5f
commit 7fd9b53308
3 changed files with 64 additions and 44 deletions
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91
ext/wasm/api/sqlite3-api-oo1.js
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@ -433,40 +433,56 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
out.returnVal = ()=>opt.resultRows;
}
if(opt.callback || opt.resultRows){
switch((undefined===opt.rowMode)
? 'array' : opt.rowMode) {
case 'object': out.cbArg = (stmt)=>stmt.get(Object.create(null)); break;
case 'array': out.cbArg = (stmt)=>stmt.get([]); break;
case 'stmt':
if(Array.isArray(opt.resultRows)){
toss3("exec(): invalid rowMode for a resultRows array: must",
"be one of 'array', 'object',",
"a result column number, or column name reference.");
}
out.cbArg = (stmt)=>stmt;
switch((undefined===opt.rowMode) ? 'array' : opt.rowMode) {
case 'object':
out.cbArg = (stmt,cache)=>{
if( !cache.columnNames ) cache.columnNames = stmt.getColumnNames([]);
/* https://sqlite.org/forum/forumpost/3632183d2470617d:
conversion of rows to objects (key/val pairs) is
somewhat expensive for large data sets because of the
native-to-JS conversion of the column names. If we
instead cache the names and build objects from that
list of strings, it can run twice as fast. The
difference is not noticeable for small data sets but
becomes human-perceivable when enough rows are
involved. */
const row = stmt.get([]);
const rv = Object.create(null);
for( const i in cache.columnNames ) rv[cache.columnNames[i]] = row[i];
return rv;
};
break;
case 'array': out.cbArg = (stmt)=>stmt.get([]); break;
case 'stmt':
if(Array.isArray(opt.resultRows)){
toss3("exec(): invalid rowMode for a resultRows array: must",
"be one of 'array', 'object',",
"a result column number, or column name reference.");
}
out.cbArg = (stmt)=>stmt;
break;
default:
if(util.isInt32(opt.rowMode)){
out.cbArg = (stmt)=>stmt.get(opt.rowMode);
break;
default:
if(util.isInt32(opt.rowMode)){
out.cbArg = (stmt)=>stmt.get(opt.rowMode);
break;
}else if('string'===typeof opt.rowMode
&& opt.rowMode.length>1
&& '$'===opt.rowMode[0]){
/* "$X": fetch column named "X" (case-sensitive!). Prior
to 2022-12-14 ":X" and "@X" were also permitted, but
having so many options is unnecessary and likely to
cause confusion. */
const $colName = opt.rowMode.substr(1);
out.cbArg = (stmt)=>{
const rc = stmt.get(Object.create(null))[$colName];
return (undefined===rc)
? toss3(capi.SQLITE_NOTFOUND,
"exec(): unknown result column:",$colName)
: rc;
};
break;
}
toss3("Invalid rowMode:",opt.rowMode);
}else if('string'===typeof opt.rowMode
&& opt.rowMode.length>1
&& '$'===opt.rowMode[0]){
/* "$X": fetch column named "X" (case-sensitive!). Prior
to 2022-12-14 ":X" and "@X" were also permitted, but
having so many options is unnecessary and likely to
cause confusion. */
const $colName = opt.rowMode.substr(1);
out.cbArg = (stmt)=>{
const rc = stmt.get(Object.create(null))[$colName];
return (undefined===rc)
? toss3(capi.SQLITE_NOTFOUND,
"exec(): unknown result column:",$colName)
: rc;
};
break;
}
toss3("Invalid rowMode:",opt.rowMode);
}
}
return out;
@ -884,10 +900,15 @@ globalThis.sqlite3ApiBootstrap.initializers.push(function(sqlite3){
and names. */) ? 0 : 1;
evalFirstResult = false;
if(arg.cbArg || resultRows){
const cbArgCache = Object.create(null)
/* 2nd arg for arg.cbArg, used by (at least) row-to-object
converter */;
for(; stmt.step(); stmt._lockedByExec = false){
if(0===gotColNames++) stmt.getColumnNames(opt.columnNames);
if(0===gotColNames++){
stmt.getColumnNames(cbArgCache.columnNames = (opt.columnNames || []));
}
stmt._lockedByExec = true;
const row = arg.cbArg(stmt);
const row = arg.cbArg(stmt,cbArgCache);
if(resultRows) resultRows.push(row);
if(callback && false === callback.call(opt, row, stmt)){
break;