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[DRAFT] Add support for TIMESTAMP types in Exasol connector #26633

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[DRAFT] Add support for TIMESTAMP types in Exasol connector #26633

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6 changes: 6 additions & 0 deletions docs/src/main/sphinx/connector/exasol.md
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Original file line number Diff line number Diff line change
Expand Up @@ -99,7 +99,13 @@ Trino data type mapping:
-
* - `DATE`
- `DATE`
-
* - `TIMESTAMP(n)`
- `TIMESTAMP(n)`
-
* - `TIMESTAMP(n) WITH LOCAL TIME ZONE`
- `TIMESTAMP(n)`
-
* - `HASHTYPE`
- `VARBINARY`
-
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146 changes: 146 additions & 0 deletions plugin/trino-exasol/src/main/java/io/trino/plugin/exasol/ExasolClient.java
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,8 @@
import io.trino.plugin.jdbc.JdbcTypeHandle;
import io.trino.plugin.jdbc.LongReadFunction;
import io.trino.plugin.jdbc.LongWriteFunction;
import io.trino.plugin.jdbc.ObjectReadFunction;
import io.trino.plugin.jdbc.ObjectWriteFunction;
import io.trino.plugin.jdbc.QueryBuilder;
import io.trino.plugin.jdbc.SliceReadFunction;
import io.trino.plugin.jdbc.SliceWriteFunction;
Expand All @@ -43,12 +45,18 @@
import io.trino.spi.connector.ColumnPosition;
import io.trino.spi.connector.ConnectorSession;
import io.trino.spi.connector.ConnectorTableMetadata;
import io.trino.spi.type.LongTimestamp;
import io.trino.spi.type.TimestampType;
import io.trino.spi.type.Type;

import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.sql.Types;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.HexFormat;
import java.util.List;
import java.util.Map;
Expand All @@ -57,20 +65,27 @@
import java.util.Set;
import java.util.function.BiFunction;

import static com.google.common.base.Preconditions.checkArgument;
import static io.trino.plugin.jdbc.PredicatePushdownController.FULL_PUSHDOWN;
import static io.trino.plugin.jdbc.StandardColumnMappings.bigintColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.booleanColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.decimalColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.defaultCharColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.defaultVarcharColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.doubleColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.fromLongTrinoTimestamp;
import static io.trino.plugin.jdbc.StandardColumnMappings.fromTrinoTimestamp;
import static io.trino.plugin.jdbc.StandardColumnMappings.integerColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.smallintColumnMapping;
import static io.trino.plugin.jdbc.StandardColumnMappings.toLongTrinoTimestamp;
import static io.trino.plugin.jdbc.StandardColumnMappings.toTrinoTimestamp;
import static io.trino.plugin.jdbc.TypeHandlingJdbcSessionProperties.getUnsupportedTypeHandling;
import static io.trino.plugin.jdbc.UnsupportedTypeHandling.CONVERT_TO_VARCHAR;
import static io.trino.spi.StandardErrorCode.NOT_SUPPORTED;
import static io.trino.spi.connector.ConnectorMetadata.MODIFYING_ROWS_MESSAGE;
import static io.trino.spi.type.DateType.DATE;
import static io.trino.spi.type.DecimalType.createDecimalType;
import static io.trino.spi.type.TimestampType.createTimestampType;
import static io.trino.spi.type.VarbinaryType.VARBINARY;
import static java.lang.String.format;
import static java.util.Locale.ENGLISH;
Expand All @@ -79,11 +94,15 @@
public class ExasolClient
extends BaseJdbcClient
{
private static final int EXASOL_TIMESTAMP_WITH_TIMEZONE = 124;

private static final Set<String> INTERNAL_SCHEMAS = ImmutableSet.<String>builder()
.add("EXA_STATISTICS")
.add("SYS")
.build();

private static final int MAX_EXASOL_TIMESTAMP_PRECISION = 9;

@Inject
public ExasolClient(
BaseJdbcConfig config,
Expand Down Expand Up @@ -239,8 +258,13 @@ public Optional<ColumnMapping> toColumnMapping(ConnectorSession session, Connect
// String data is sorted by its binary representation.
// https://docs.exasol.com/db/latest/sql/select.htm#UsageNotes
return Optional.of(defaultVarcharColumnMapping(typeHandle.requiredColumnSize(), true));
// DATE, TIMESTAMP and TIMESTAMP WITH LOCAL TIME ZONE types are described here in more details:
// https://docs.exasol.com/db/latest/sql_references/data_types/datatypedetails.htm
case Types.DATE:
return Optional.of(dateColumnMapping());
case Types.TIMESTAMP:
case EXASOL_TIMESTAMP_WITH_TIMEZONE:
return Optional.of(timestampColumnMapping(typeHandle));
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The https://docs.exasol.com/db/latest/sql_references/data_types/datatypedetails.htm#Dateandtimedatatypes shows that timestamp with local time zone type actually has timezone concept, but just store as UTC.

How about support only TIMESTAMP type first in this single pr?

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The https://docs.exasol.com/db/latest/sql_references/data_types/datatypedetails.htm#Dateandtimedatatypes shows that timestamp with local time zone type actually has timezone concept, but just store as UTC.

Yes, it has some differences in the time zone behavior, than usual TIMESTAMP, which are reflected in the tests, but when we get the actual column value with trino connector reader we don't know, in which time zone it was saved. So if we map to Trino "Timestamp With Time Zone" we must provide some time zone, which could be hardcoded UTC or JVM Time Zone. But this approach is more fragile and in some extreme cases like DLT, could even provide incorrect mapping. So the solution of mapping to Trino Timestamp is more simple and less error-prone.

How about support only TIMESTAMP type first in this single pr?

The implementations are actually very similar and the second PR would be a change of just two lines of code in the main source and one line in documentation (the tests are also very similar for each type).
This is due to a more simple solution, which maps to Trino Timestamp for both Exasol Types.

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@skyglass skyglass Oct 15, 2025 •
edited
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Thank you very much for your review, @chenjian2664 👍

The new PR, which contains only TIMESTAMP changes, has been created:
#26963

I will close this PR

}

if (getUnsupportedTypeHandling(session) == CONVERT_TO_VARCHAR) {
Expand All @@ -256,6 +280,128 @@ private boolean isHashType(JdbcTypeHandle typeHandle)
&& typeHandle.jdbcTypeName().get().equalsIgnoreCase("HASHTYPE");
}

private static ColumnMapping timestampColumnMapping(JdbcTypeHandle typeHandle)
{
int timestampPrecision = typeHandle.requiredDecimalDigits();
TimestampType timestampType = createTimestampType(timestampPrecision);
if (timestampType.isShort()) {
return ColumnMapping.longMapping(
timestampType,
longTimestampReadFunction(timestampType),
longTimestampWriteFunction(timestampType),
FULL_PUSHDOWN);
}
return ColumnMapping.objectMapping(
timestampType,
objectTimestampReadFunction(timestampType),
objectTimestampWriteFunction(timestampType),
FULL_PUSHDOWN);
}

private static LongReadFunction longTimestampReadFunction(TimestampType timestampType)
{
return (resultSet, columnIndex) -> {
Timestamp timestamp = resultSet.getTimestamp(columnIndex);
return toTrinoTimestamp(timestampType, timestamp.toLocalDateTime());
};
}

private static LongWriteFunction longTimestampWriteFunction(TimestampType timestampType)
{
return new LongWriteFunction()
{
@Override
public String getBindExpression()
{
return getTimestampBindExpression(timestampType.getPrecision());
}

@Override
public void set(PreparedStatement statement, int index, long epochMicros)
throws SQLException
{
LocalDateTime localDateTime = fromTrinoTimestamp(epochMicros);
Timestamp timestampValue = Timestamp.valueOf(localDateTime);
statement.setTimestamp(index, timestampValue);
}

@Override
public void setNull(PreparedStatement statement, int index)
throws SQLException
{
statement.setNull(index, Types.VARCHAR);
}
};
}

private static ObjectReadFunction objectTimestampReadFunction(TimestampType timestampType)
{
verifyObjectTimestampPrecision(timestampType);
return ObjectReadFunction.of(
LongTimestamp.class,
(resultSet, columnIndex) -> {
Timestamp timestamp = resultSet.getTimestamp(columnIndex);
return toLongTrinoTimestamp(timestampType, timestamp.toLocalDateTime());
});
}

private static ObjectWriteFunction objectTimestampWriteFunction(TimestampType timestampType)
{
int precision = timestampType.getPrecision();
verifyObjectTimestampPrecision(timestampType);

return new ObjectWriteFunction() {
@Override
public Class<?> getJavaType()
{
return LongTimestamp.class;
}

@Override
public void set(PreparedStatement statement, int index, Object value)
throws SQLException
{
LocalDateTime localDateTime = fromLongTrinoTimestamp((LongTimestamp) value, precision);
Timestamp timestamp = Timestamp.valueOf(localDateTime);
statement.setTimestamp(index, timestamp);
}

@Override
public String getBindExpression()
{
return getTimestampBindExpression(timestampType.getPrecision());
}

@Override
public void setNull(PreparedStatement statement, int index)
throws SQLException
{
statement.setNull(index, Types.VARCHAR);
}
};
}

private static void verifyObjectTimestampPrecision(TimestampType timestampType)
{
int precision = timestampType.getPrecision();
checkArgument(precision > TimestampType.MAX_SHORT_PRECISION && precision <= MAX_EXASOL_TIMESTAMP_PRECISION,
"Precision is out of range: %s", precision);
}

/**
* Returns a {@code TO_TIMESTAMP} bind expression using the appropriate format model
* based on the given fractional seconds precision.
* See for more details: <a href="https://docs.exasol.com/db/latest/sql_references/formatmodels.htm">Date/time format models</a>
*/
private static String getTimestampBindExpression(int precision)
{
checkArgument(precision >= 0, "Precision is negative: %s", precision);
if (precision == 0) {
return "TO_TIMESTAMP(?, 'YYYY-MM-DD HH24:MI:SS')";
}
return format("TO_TIMESTAMP(?, 'YYYY-MM-DD HH24:MI:SS.FF%d')", precision);
}

private static ColumnMapping dateColumnMapping()
{
// Exasol driver does not support LocalDate
Expand Down
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