Pietro created FLINK-35053:
------------------------------
Summary: TIMESTAMP with TIME ZONE not supported by JDBC connector
for Postgres
Key: FLINK-35053
URL: https://issues.apache.org/jira/browse/FLINK-35053
Project: Flink
Issue Type: Bug
Components: Connectors / JDBC
Affects Versions: jdbc-3.1.2, 1.18.1, 1.19.0
Reporter: Pietro
The JDBC sink for Postgres does not support {{{}TIMESTAMP WITH TIME ZONE{}}},
nor {{TIMESTAMP_LTZ}} types.
Related issues: FLINK-22199, FLINK-20869
h2. Problem Explanation
A Postgres {{target_table}} has a field {{tm_tz}} of type {{timestamptz}} .
{code:sql}
-- Postgres DDL
CREATE TABLE target_table (
tm_tz TIMESTAMP WITH TIME ZONE
)
{code}
In Flink we have a table with a column of type {{{}TIMESTAMP_LTZ(6){}}}, and
our goal is to sink it to {{{}target_table{}}}.
{code:sql}
-- Flink DDL
CREATE TABLE sink (
tm_tz TIMESTAMP_LTZ(6)
) WITH (
'connector' = 'jdbc',
'table-name' = 'target_table'
...
)
{code}
According to
[AbstractPostgresCompatibleDialect.supportedTypes()|https://github.com/apache/flink-connector-jdbc/blob/7025642d88ff661e486745b23569595e1813a1d0/flink-connector-jdbc/src/main/java/org/apache/flink/connector/jdbc/dialect/AbstractPostgresCompatibleDialect.java#L109],
{{TIMESTAMP_WITH_LOCAL_TIME_ZONE}} is supported, while
{{TIMESTAMP_WITH_TIME_ZONE}} is not.
However, when the converter is created via
[AbstractJdbcRowConverter.createInternalConverter()|https://github.com/apache/flink-connector-jdbc/blob/7025642d88ff661e486745b23569595e1813a1d0/flink-connector-jdbc/src/main/java/org/apache/flink/connector/jdbc/converter/AbstractJdbcRowConverter.java#L132],
it throws an {{UnsupportedOperationException}} since
{{TIMESTAMP_WITH_LOCAL_TIME_ZONE}} is *not* among the available types, while
[{{TIMESTAMP_WITH_TIME_ZONE}}|https://github.com/apache/flink-connector-jdbc/blob/7025642d88ff661e486745b23569595e1813a1d0/flink-connector-jdbc/src/main/java/org/apache/flink/connector/jdbc/converter/AbstractJdbcRowConverter.java#L168]
is.
{code:java}
Exception in thread "main" java.lang.UnsupportedOperationException: Unsupported
type:TIMESTAMP_LTZ(6)
at
org.apache.flink.connector.jdbc.converter.AbstractJdbcRowConverter.createInternalConverter(AbstractJdbcRowConverter.java:186)
at
org.apache.flink.connector.jdbc.databases.postgres.dialect.PostgresRowConverter.createPrimitiveConverter(PostgresRowConverter.java:99)
at
org.apache.flink.connector.jdbc.databases.postgres.dialect.PostgresRowConverter.createInternalConverter(PostgresRowConverter.java:58)
at
org.apache.flink.connector.jdbc.converter.AbstractJdbcRowConverter.createNullableInternalConverter(AbstractJdbcRowConverter.java:118)
at
org.apache.flink.connector.jdbc.converter.AbstractJdbcRowConverter.<init>(AbstractJdbcRowConverter.java:68)
at
org.apache.flink.connector.jdbc.databases.postgres.dialect.PostgresRowConverter.<init>(PostgresRowConverter.java:47)
at
org.apache.flink.connector.jdbc.databases.postgres.dialect.PostgresDialect.getRowConverter(PostgresDialect.java:51)
at
org.apache.flink.connector.jdbc.table.JdbcDynamicTableSource.getScanRuntimeProvider(JdbcDynamicTableSource.java:184)
at
org.apache.flink.table.planner.connectors.DynamicSourceUtils.validateScanSource(DynamicSourceUtils.java:478)
at
org.apache.flink.table.planner.connectors.DynamicSourceUtils.prepareDynamicSource(DynamicSourceUtils.java:161)
at
org.apache.flink.table.planner.connectors.DynamicSourceUtils.convertSourceToRel(DynamicSourceUtils.java:125)
at
org.apache.flink.table.planner.plan.schema.CatalogSourceTable.toRel(CatalogSourceTable.java:118)
at
org.apache.calcite.sql2rel.SqlToRelConverter.toRel(SqlToRelConverter.java:4002)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertIdentifier(SqlToRelConverter.java:2872)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertFrom(SqlToRelConverter.java:2432)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertFrom(SqlToRelConverter.java:2346)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertFrom(SqlToRelConverter.java:2291)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertSelectImpl(SqlToRelConverter.java:728)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertSelect(SqlToRelConverter.java:714)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertQueryRecursive(SqlToRelConverter.java:3848)
at
org.apache.calcite.sql2rel.SqlToRelConverter.convertQuery(SqlToRelConverter.java:618)
at
org.apache.flink.table.planner.calcite.FlinkPlannerImpl.org$apache$flink$table$planner$calcite$FlinkPlannerImpl$$rel(FlinkPlannerImpl.scala:229)
at
org.apache.flink.table.planner.calcite.FlinkPlannerImpl.rel(FlinkPlannerImpl.scala:205)
at
org.apache.flink.table.planner.operations.SqlNodeConvertContext.toRelRoot(SqlNodeConvertContext.java:69)
at
org.apache.flink.table.planner.operations.converters.SqlQueryConverter.convertSqlNode(SqlQueryConverter.java:48)
at
org.apache.flink.table.planner.operations.converters.SqlNodeConverters.convertSqlNode(SqlNodeConverters.java:73)
at
org.apache.flink.table.planner.operations.SqlNodeToOperationConversion.convertValidatedSqlNode(SqlNodeToOperationConversion.java:272)
at
org.apache.flink.table.planner.operations.SqlNodeToOperationConversion.convert(SqlNodeToOperationConversion.java:262)
at
org.apache.flink.table.planner.delegation.ParserImpl.parse(ParserImpl.java:106)
at
org.apache.flink.table.api.internal.TableEnvironmentImpl.sqlQuery(TableEnvironmentImpl.java:708)
{code}
h3. Using TIMESTAMP WITH TIME ZONE
Defining {{tm_tz}} in Flink as {{TIMESTAMP(6) WITH TIME ZONE}} instead of
{{TIMESTAMP_LTZ(6)}} does not solve the issue, and returns the following error
instead:
{code:java}
Exception in thread "main" org.apache.flink.table.api.SqlParserException: SQL
parse failed. Encountered "TIME" at line 1, column 66.
Was expecting:
"LOCAL" ...
at
org.apache.flink.table.planner.parse.CalciteParser.parseSqlList(CalciteParser.java:81)
at
org.apache.flink.table.planner.delegation.ParserImpl.parse(ParserImpl.java:102)
at
org.apache.flink.table.api.internal.TableEnvironmentImpl.executeSql(TableEnvironmentImpl.java:728)
{code}
h3. Using TIMESTAMP
Defining {{tm_tz}} in Flink as {{TIMESTAMP(6)}} can lead to potentially
incorrect time zone conversions because Postgres interprets timestamps without
an explicit time zone indication as if they were in the in the system's time
zone (reference: [Postgres
Documentation|https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-DATETIME-INPUT-TIME-STAMPS]).
For instance, assume that Postgres is in GMT+2 time zone. If in Flink we have
the timestamp {{'2024-04-08 00:00:00'}} (UTC), then, when inserted into
Postgres, it gets interpreted as if it is in GMT+2 and stored as
{{{}'2024-04-07 22:00:00+00'{}}}.
To ensure that Postgres interprets it correctly, it should be passed by Flink
as {{'2024-04-08 00:00:00+00'}} (notice the trailing {{{}'+00'{}}})
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