Yann Landrin-Schweitzer created BEAM-10946:
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Summary: JdbcIO should make the 'COMMENT' metadata available as
Description
Key: BEAM-10946
URL: https://issues.apache.org/jira/browse/BEAM-10946
Project: Beam
Issue Type: Improvement
Components: io-java-jdbc
Affects Versions: 2.23.0
Reporter: Yann Landrin-Schweitzer
Currently, creating a PCollection<Row> using JdbcIO.readRows() does not make
available:
- a column's COMMENT or REMARKS metadata as the corresponding Beam field
Description
- a table COMMENT or REMARKS metadata as an appropriately named Beam schema
Option
Making this metadata available would strongly benefit IDEs providing in-line
help to create Beam pipelines, as well as semi-automated data labelling tools
using metadata to infer data properties.
Sketch of the proposed changes in JdbcIO:
{code:java}
@FunctionalInterface
interface BeamFieldConverter extends Serializable {
Schema.Field create(int index, ResultSetMetaData md, DatabaseMetaData dmd)
throws SQLException;
}
private static String getComment(int index, ResultSetMetaData md,
DatabaseMetaData dmd) throws SQLException {
String comment = null;
if(dmd instanceof DatabaseMetaDataUsingInfoSchema) {
ResultSet rs = dmd.getColumns(md.getCatalogName(index),
md.getSchemaName(index), md.getTableName(index), md.getColumnName(index));
if(rs.next()
&& md.getTableName(index).equals(rs.getString("TABLE_NAME"))
&& md.getColumnName(index).equals(rs.getString("COLUMN_NAME"))
) {
comment = rs.getString("REMARKS");
}
}
return comment;
}
{code}
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