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Improve performance of json functions #22348

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Merged
merged 1 commit into from
Jun 12, 2024
Merged

Improve performance of json functions #22348

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11 changes: 10 additions & 1 deletion core/trino-main/src/main/java/io/trino/util/JsonUtil.java
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.StringReader;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.HashMap;
Expand Down Expand Up @@ -105,6 +106,9 @@

public final class JsonUtil
{
// StringReader outperforms InputStreamReader for small inputs. Limit based on Jackson benchmarks {@link https://github.com/FasterXML/jackson-benchmarks/pull/9}
private static final int STRING_READER_LENGTH_LIMIT = 8192;

private JsonUtil() {}

// This object mapper is constructed without .configure(ORDER_MAP_ENTRIES_BY_KEYS, true) because
Expand All @@ -124,7 +128,12 @@ public static JsonParser createJsonParser(JsonFactory factory, Slice json)
throws IOException
{
// Jackson tries to detect the character encoding automatically when using InputStream
// so we pass an InputStreamReader instead.
// so we pass StringReader or an InputStreamReader instead.
if (json.length() < STRING_READER_LENGTH_LIMIT) {
// StringReader is more performant than InputStreamReader for small inputs
return factory.createParser(new StringReader(new String(json.getBytes(), UTF_8)));
}

return factory.createParser(new InputStreamReader(json.getInput(), UTF_8));
}

Expand Down