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perf(spanner-jdbc): cache JDBC metadata query strings #14041

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perf(spanner-jdbc): cache JDBC metadata query strings #14041

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ad97128
perf(spanner-jdbc): cache JDBC metadata query strings
olavloite Aug 11, 2026
62447b1
Merge branch 'main' into cache-metadata-queries
olavloite Aug 13, 2026
14bac61
chore(spanner-jdbc): address review comments
olavloite Aug 13, 2026
f6db9ea
Merge branch 'main' into cache-metadata-queries
rahul2393 Aug 18, 2026
40d5d98
test(spanner-jdbc): unflake sample tests
olavloite Aug 19, 2026
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25 changes: 15 additions & 10 deletions java-spanner-jdbc/src/main/java/com/google/cloud/spanner/jdbc/JdbcDatabaseMetaData.java
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Original file line number Diff line number Diff line change
Expand Up @@ -26,10 +26,12 @@
import com.google.cloud.spanner.Type.StructField;
import com.google.cloud.spanner.connection.Connection.InternalMetadataQuery;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.ResultSet;
Expand All @@ -40,6 +42,8 @@
import java.util.Collections;
import java.util.Properties;
import java.util.Scanner;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/** {@link DatabaseMetaData} implementation for Cloud Spanner */
class JdbcDatabaseMetaData extends AbstractJdbcWrapper implements DatabaseMetaData {
Expand All @@ -50,18 +54,19 @@ class JdbcDatabaseMetaData extends AbstractJdbcWrapper implements DatabaseMetaDa
private static final String PRODUCT_NAME = "Google Cloud Spanner";
private static final String POSTGRESQL_PRODUCT_NAME = PRODUCT_NAME + " PostgreSQL";

private static final ConcurrentMap<String, String> SQL_CACHE = new ConcurrentHashMap<>();

@VisibleForTesting
static String readSqlFromFile(String filename, Dialect dialect) {
InputStream in;
switch (dialect) {
case POSTGRESQL:
in = JdbcDatabaseMetaData.class.getResourceAsStream("postgresql/" + filename);
break;
case GOOGLE_STANDARD_SQL:
default:
in = JdbcDatabaseMetaData.class.getResourceAsStream(filename);
}
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
return SQL_CACHE.computeIfAbsent(
filename + "/" + dialect, (key) -> loadSqlFromFile(filename, dialect));
}
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private static String loadSqlFromFile(String filename, Dialect dialect) {
String resourcePath = dialect == Dialect.POSTGRESQL ? "postgresql/" + filename : filename;
InputStream in = JdbcDatabaseMetaData.class.getResourceAsStream(resourcePath);
Preconditions.checkNotNull(in, "Resource not found: " + resourcePath);
BufferedReader reader = new BufferedReader(new InputStreamReader(in, StandardCharsets.UTF_8));
StringBuilder builder = new StringBuilder();
try (Scanner scanner = new Scanner(reader)) {
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while (scanner.hasNextLine()) {
Expand Down
9 changes: 9 additions & 0 deletions java-spanner-jdbc/src/test/java/com/google/cloud/spanner/jdbc/JdbcDatabaseMetaDataTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertSame;
import static org.junit.Assert.assertTrue;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;
Expand Down Expand Up @@ -574,4 +575,12 @@ public void testGetUserName() throws SQLException, IOException {
DatabaseMetaData meta = new JdbcDatabaseMetaData(connection);
assertEquals("test@test-project.iam.gserviceaccount.com", meta.getUserName());
}

@Test
public void testReadSqlFromFileCaching() {
String sql1 = JdbcDatabaseMetaData.readSqlFromFile("DatabaseMetaData_GetTables.sql", dialect);
String sql2 = JdbcDatabaseMetaData.readSqlFromFile("DatabaseMetaData_GetTables.sql", dialect);
assertNotNull(sql1);
assertSame(sql1, sql2);
}
}
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