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Core: Fix caching table with metadata table names #11123

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37 changes: 21 additions & 16 deletions core/src/main/java/org/apache/iceberg/CachingCatalog.java
Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
import org.apache.iceberg.catalog.Namespace;
import org.apache.iceberg.catalog.TableIdentifier;
import org.apache.iceberg.exceptions.AlreadyExistsException;
import org.apache.iceberg.exceptions.NoSuchTableException;
import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
import org.slf4j.Logger;
Expand Down Expand Up @@ -145,22 +146,26 @@ public Table loadTable(TableIdentifier ident) {
}

if (MetadataTableUtils.hasMetadataTableName(canonicalized)) {
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FWIW, as I see the RESTSessionCatalog does this the other way around: First tries to load the table as a regular table and then if that fails it tries to load it as a metadata table. https://github.com/apache/iceberg/blob/main/core/src/main/java/org/apache/iceberg/rest/RESTSessionCatalog.java#L461
I find that approach cleaner, but let me know what you think.

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Do you suggest we call catalog::loadTable first? If so, we might not be able to cache the original table, since the underlying catalog can load the metadata table directly.

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What I had in mind was something different:
try {
return tableCache.get(canonicalized, catalog::loadTable);
} catch (NoSuchTableException) {
// Verify it's a metadata table
// Do whatever we want in case of a metadata table, even cache the original table.
}
What do you think?

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@manuzhang manuzhang Nov 26, 2024

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The issue is noNoSuchTableException will ever be thrown on cache miss since catalog::loadTable can successfully load the metadata table. For example, in BaseMetastoreCatalog

public Table loadTable(TableIdentifier identifier) {
Table result;
if (isValidIdentifier(identifier)) {
TableOperations ops = newTableOps(identifier);
if (ops.current() == null) {
// the identifier may be valid for both tables and metadata tables
if (isValidMetadataIdentifier(identifier)) {
result = loadMetadataTable(identifier);
} else {
throw new NoSuchTableException("Table does not exist: %s", identifier);
}
} else {
result = new BaseTable(ops, fullTableName(name(), identifier), metricsReporter());
}
} else if (isValidMetadataIdentifier(identifier)) {
result = loadMetadataTable(identifier);
} else {
throw new NoSuchTableException("Invalid table identifier: %s", identifier);
}
LOG.info("Table loaded by catalog: {}", result);
return result;
}

In this case, we don't cache the original table and change the current behavior.

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Finally I had some time to take a deeper look on this. You are right, with my above proposal we won't run the specific code for metadata tables like caching the underlying table and sharing the table operations.

I did find a way simpler version of this fix, however. I also wrote some tests in TestCachingCatalog. gaborkaszab@c1eca8b
What do you think? Would you mind if I opened an alternative fix PR?

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Please go ahead.

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Thanks @manuzhang !
I created this PR for the alternative fix: #11738 Added you as a co-author.
@RussellSpitzer I saw your thumbs-up on one of my comments. Would you mind taking a look at the PR?

TableIdentifier originTableIdentifier =
TableIdentifier.of(canonicalized.namespace().levels());
Table originTable = tableCache.get(originTableIdentifier, catalog::loadTable);

// share TableOperations instance of origin table for all metadata tables, so that metadata
// table instances are
// also refreshed as well when origin table instance is refreshed.
if (originTable instanceof HasTableOperations) {
TableOperations ops = ((HasTableOperations) originTable).operations();
MetadataTableType type = MetadataTableType.from(canonicalized.name());

Table metadataTable =
MetadataTableUtils.createMetadataTableInstance(
ops, catalog.name(), originTableIdentifier, canonicalized, type);
tableCache.put(canonicalized, metadataTable);
return metadataTable;
try {
TableIdentifier originTableIdentifier =
TableIdentifier.of(canonicalized.namespace().levels());
Table originTable = tableCache.get(originTableIdentifier, catalog::loadTable);

// share TableOperations instance of origin table for all metadata tables, so that metadata
// table instances are
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nit: I know there was only an indentation change here, but there is an odd linebreak in this line

// also refreshed as well when origin table instance is refreshed.
if (originTable instanceof HasTableOperations) {
TableOperations ops = ((HasTableOperations) originTable).operations();
MetadataTableType type = MetadataTableType.from(canonicalized.name());

Table metadataTable =
MetadataTableUtils.createMetadataTableInstance(
ops, catalog.name(), originTableIdentifier, canonicalized, type);
tableCache.put(canonicalized, metadataTable);
return metadataTable;
}
} catch (NoSuchTableException e) {
// it's not a metadata table so ignore exception and load as a normal table
}
}

Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,89 @@
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* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.iceberg.spark.sql;

import java.util.List;
import org.apache.iceberg.Parameter;
import org.apache.iceberg.Parameters;
import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
import org.apache.iceberg.relocated.com.google.common.collect.ImmutableMap;
import org.apache.iceberg.spark.CatalogTestBase;
import org.apache.iceberg.spark.SparkCatalogConfig;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.TestTemplate;

public class TestCachingTableWithMetaTableName extends CatalogTestBase {
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I found that there is an existing test suite, TestCachingCatalog. Wouldn't it be cleaner to add test coverage there instead of to the Spark test suite?

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That test is to test CachingCatalog itself. This test is to test caching behavior in a real catalog.

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I get that, but I think this patch did change the CachingCatalog internals itself, I don't see what is the additional value in putting this into a Spark test. TestCachingCatalog should definitely have coverage for behaviours like this. If you feel that an additional Spark test is also beneficial, I don't mind. I might miss some background, though.

private static final String TABLE_NAME = "history";

@Parameter(index = 3)
private int cacheExpirationInterval;

@Parameters(
name = "catalogName = {0}, implementation = {1}, config = {2}, cacheExpirationInterval = {3}")
protected static Object[][] parameters() {
return new Object[][] {
{
SparkCatalogConfig.SPARK.catalogName(),
SparkCatalogConfig.SPARK.implementation(),
ImmutableMap.of(
"type", "hive",
"default-namespace", "default",
"parquet-enabled", "true",
"cache-enabled", "true"),
1
},
{
SparkCatalogConfig.SPARK.catalogName(),
SparkCatalogConfig.SPARK.implementation(),
ImmutableMap.of(
"type", "hive",
"default-namespace", "default",
"parquet-enabled", "true",
"cache-enabled", "true"),
-1
}
};
}

@BeforeEach
public void createTables() {
spark
.conf()
.set(
"spark.sql.catalog.spark_catalog.cache.expiration-interval-ms",
cacheExpirationInterval);
sql("CREATE TABLE %s (id bigint, data string, float float) USING iceberg", TABLE_NAME);
}

@AfterEach
public void removeTables() {
sql("DROP TABLE IF EXISTS %s", TABLE_NAME);
}

@TestTemplate
public void testLoadTableAfterCacheExpires() throws InterruptedException {
Thread.sleep(10); // wait for cache to expire
sql("INSERT INTO %s VALUES (1, 'a', 1.0), (2, 'b', 2.0), (3, 'c', float('NaN'))", TABLE_NAME);
List<Object[]> expected =
ImmutableList.of(row(1L, "a", 1.0F), row(2L, "b", 2.0F), row(3L, "c", Float.NaN));

assertEquals("Should return all expected rows", expected, sql("SELECT * FROM %s", TABLE_NAME));
}
}