Collect NDV stats on all columns when replacing Iceberg tables #27014
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Reviewer's GuidePropagate a replace flag in statistics collection metadata APIs to enable collecting NDV stats on all columns during table replace operations, updating core SPI, metadata propagation, planners, tracing and wrapper layers, Iceberg connector implementation, and adding a test to validate SHOW STATS after REPLACE TABLE. Sequence diagram for statistics collection during table replace operationsequenceDiagram
participant Planner
participant MetadataManager
participant ConnectorMetadata
participant IcebergMetadata
Planner->>MetadataManager: getStatisticsCollectionMetadataForWrite(..., replace=true)
MetadataManager->>ConnectorMetadata: getStatisticsCollectionMetadataForWrite(..., replace=true)
ConnectorMetadata->>IcebergMetadata: getStatisticsCollectionMetadataForWrite(..., replace=true)
IcebergMetadata-->>ConnectorMetadata: TableStatisticsMetadata (NDV stats on all columns)
ConnectorMetadata-->>MetadataManager: TableStatisticsMetadata
MetadataManager-->>Planner: TableStatisticsMetadata
Class diagram for updated statistics collection metadata APIsclassDiagram
class Metadata {
+getStatisticsCollectionMetadataForWrite(Session session, CatalogHandle catalogHandle, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
}
class MetadataManager {
+getStatisticsCollectionMetadataForWrite(Session session, CatalogHandle catalogHandle, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
}
class TracingMetadata {
+getStatisticsCollectionMetadataForWrite(Session session, CatalogHandle catalogHandle, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
}
class ConnectorMetadata {
+getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
+getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata): TableStatisticsMetadata (deprecated)
}
class TracingConnectorMetadata {
+getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
}
class ClassLoaderSafeConnectorMetadata {
+getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
}
class IcebergMetadata {
+getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
}
class LakehouseMetadata {
+getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace): TableStatisticsMetadata
}
MetadataManager --> Metadata
TracingMetadata --> MetadataManager
TracingConnectorMetadata --> ConnectorMetadata
ClassLoaderSafeConnectorMetadata --> ConnectorMetadata
IcebergMetadata --> ConnectorMetadata
LakehouseMetadata --> ConnectorMetadata
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Hey there - I've reviewed your changes and they look great!
Prompt for AI Agents
Please address the comments from this code review:
## Individual Comments
### Comment 1
<location> `core/trino-main/src/main/java/io/trino/tracing/TracingMetadata.java:633` </location>
<code_context>
}
@Override
- public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(Session session, CatalogHandle catalogHandle, ConnectorTableMetadata tableMetadata)
+ public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(Session session, CatalogHandle catalogHandle, ConnectorTableMetadata tableMetadata, boolean replace)
{
CatalogMetadata catalogMetadata = getCatalogMetadataForWrite(session, catalogHandle);
</code_context>
<issue_to_address>
**suggestion:** Tracing wrapper passes 'replace' but does not log or trace its value.
If 'replace' impacts statistics collection, add its value to the tracing span to improve observability.
</issue_to_address>
### Comment 2
<location> `lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/classloader/ClassLoaderSafeConnectorMetadata.java:158` </location>
<code_context>
}
@Override
- public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata)
+ public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace)
{
Span span = startSpan("getStatisticsCollectionMetadataForWrite", tableMetadata.getTable());
</code_context>
<issue_to_address>
**issue:** ClassLoaderSafeConnectorMetadata now passes 'replace', but does not handle backward compatibility.
If the delegate lacks the updated method, runtime errors may occur. Please add a fallback to the deprecated method to maintain compatibility.
</issue_to_address>
### Comment 3
<location> `plugin/trino-iceberg/src/test/java/io/trino/plugin/iceberg/TestIcebergStatistics.java:976-974` </location>
<code_context>
+ @Test
</code_context>
<issue_to_address>
**suggestion (testing):** Consider adding tests for error conditions and edge cases in table replacement.
Please add tests for cases like replacing tables with no columns, columns of varying types, duplicate column names, replacement failures, and when extended statistics are disabled.
Suggested implementation:
```java
@Test
public void testShowStatsReplaceTable()
{
try (TestTable table = newTrinoTable("show_stats_after_replace_table_", "AS SELECT 1 a, 2 b")) {
assertThat(query("SHOW STATS FOR " + table.getName()))
.skippingTypesCheck()
.matches("""
VALUES
('a', null, 1e0, 0e0, NULL, '1', '1'),
('b', null, 1e0, 0e0, NULL, '2', '2'),
(NULL, NULL, NULL, NULL, 1e0, NULL, NULL)
""");
}
}
@Test
public void testReplaceTableWithNoColumns()
{
try (TestTable table = newTrinoTable("replace_table_no_columns", "(a INTEGER)")) {
assertUpdate("REPLACE TABLE " + table.getName() + " AS SELECT"); // No columns
assertThat(query("SHOW STATS FOR " + table.getName()))
.skippingTypesCheck()
.matches("""
VALUES
(NULL, NULL, NULL, NULL, 0e0, NULL, NULL)
""");
}
}
@Test
public void testReplaceTableWithVaryingColumnTypes()
{
try (TestTable table = newTrinoTable("replace_table_varying_types", "(a INTEGER, b VARCHAR, c DOUBLE)")) {
assertUpdate("REPLACE TABLE " + table.getName() + " AS SELECT 1 a, 'x' b, 3.14 c");
assertThat(query("SHOW STATS FOR " + table.getName()))
.skippingTypesCheck()
.matches("""
VALUES
('a', null, 1e0, 0e0, NULL, '1', '1'),
('b', null, 1e0, 0e0, NULL, 'x', 'x'),
('c', null, 1e0, 0e0, NULL, '3.14', '3.14'),
(NULL, NULL, NULL, NULL, 1e0, NULL, NULL)
""");
}
}
@Test
public void testReplaceTableWithDuplicateColumnNames()
{
try (TestTable table = newTrinoTable("replace_table_duplicate_columns", "(a INTEGER, a INTEGER)")) {
// This should fail due to duplicate column names
assertQueryFails("REPLACE TABLE " + table.getName() + " AS SELECT 1 a, 2 a", "Duplicate column name: a");
}
}
@Test
public void testReplaceTableFailure()
{
try (TestTable table = newTrinoTable("replace_table_failure", "(a INTEGER)")) {
// Invalid SQL
assertQueryFails("REPLACE TABLE " + table.getName() + " AS SELECT invalid_column", "Column 'invalid_column' cannot be resolved");
}
}
@Test
public void testReplaceTableWithExtendedStatisticsDisabled()
{
// Assuming there is a session property or config to disable extended statistics
Session session = Session.builder(getSession())
.setCatalogSessionProperty("iceberg", "collect_extended_statistics_enabled", "false")
.build();
try (TestTable table = newTrinoTable("replace_table_ext_stats_disabled", "(a INTEGER)")) {
getQueryRunner().execute(session, "REPLACE TABLE " + table.getName() + " AS SELECT 1 a");
assertThat(query("SHOW STATS FOR " + table.getName()))
.skippingTypesCheck()
.matches("""
VALUES
('a', null, 1e0, 0e0, NULL, '1', '1'),
(NULL, NULL, NULL, NULL, 1e0, NULL, NULL)
""");
}
}
```
- If your test infrastructure does not support `assertQueryFails`, you may need to use the appropriate method for asserting query failures.
- Adjust the session property name for disabling extended statistics if it differs in your codebase.
- Ensure that `newTrinoTable` and `getQueryRunner()` are available and correctly configured for these tests.
</issue_to_address>Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.
...toolkit/src/main/java/io/trino/plugin/base/classloader/ClassLoaderSafeConnectorMetadata.java
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CI failure will be fixed by #27019 |
findepi
approved these changes
Oct 22, 2025
| } | ||
|
|
||
| if (replace) { | ||
| return getStatisticsCollectionMetadata(tableMetadata, Optional.empty(), _ -> {}); |
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keep it consistent with the 3 other occurrences of return getStatisticsCollectionMetadata(tableMetadata, Optional.empty(), availableColumnNames -> {}); below
Suggested change
| return getStatisticsCollectionMetadata(tableMetadata, Optional.empty(), _ -> {}); | |
| return getStatisticsCollectionMetadata(tableMetadata, Optional.empty(), availableColumnNames -> {}); |
|
|
||
| @Override | ||
| public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata) | ||
| public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace) |
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does it allow removal of exclusion in TestLakehouseMetadata ?
|
|
||
| @Override | ||
| public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata) | ||
| public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace) |
There was a problem hiding this comment.
add
@Override
public TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata)
{
throw new UnsupportedOperationException("This variant of getStatisticsCollectionMetadataForWrite is unsupported");
}| /** | ||
| * Describes statistics that must be collected during a write. | ||
| */ | ||
| default TableStatisticsMetadata getStatisticsCollectionMetadataForWrite(ConnectorSession session, ConnectorTableMetadata tableMetadata, boolean replace) |
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replace -> tableReplace
and add @param javadoc
in the context of this method it's quite not obvious what "replace" could mean
eg is it "replace old statistics" maybe?
ebyhr
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CI hit #23596 |
findepi
reviewed
Oct 22, 2025
| /** | ||
| * Describes statistics that must be collected during a write. | ||
| * | ||
| * @param tableReplace if true, replace old statistics |
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"indicates whether this is for table replace operation and statistics of an existing table (if any) should be ignored"
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Description
Fixes #26983
Release notes
Summary by Sourcery
Enable collection of distinct value statistics on all columns when replacing Iceberg tables by extending the statistics collection API with a replace flag and updating the Iceberg connector to use it.
New Features:
replaceflag in the statistics collection SPI and propagate it through core, planner, tracing, and connector layers to distinguish replacement writesEnhancements:
replaceparameterTests: