dengzhhu653 commented on code in PR #4475:
URL: https://github.com/apache/hive/pull/4475#discussion_r1267505725
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jdbc-handler/src/main/java/org/apache/hive/storage/jdbc/dao/HiveDatabaseAccessor.java:
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@@ -56,4 +57,19 @@ protected String addLimitToQuery(String sql, int limit) {
}
return sql + " LIMIT " + limit;
}
+
+ @Override
+ protected List<String> getColNamesFromRS(ResultSet rs) throws Exception {
+ List<String> columnNames = super.getColNamesFromRS(rs);
+ return columnNames.stream()
+ .map(c -> {
+ int lastIndex = c.lastIndexOf(".");
+ return lastIndex == -1 ? c : c.substring(lastIndex + 1); })
+ .collect(Collectors.toList());
+ }
+
+ @Override
+ protected String getMetaDataQuery(String sql) {
+ return addLimitToQuery(sql, 0);
Review Comment:
The default implement of getMetaDataQuery is actually adding `limit 1` to
the`sql`,
https://github.com/apache/hive/blob/a838ca2760799708c465051904b96cab4ae628d1/jdbc-handler/src/main/java/org/apache/hive/storage/jdbc/dao/GenericJdbcDatabaseAccessor.java#L176-L178
I guess in some db vendors, `limit 0` will get an empty metadata of the
result, that's why we cannot call `addLimitToQuery(sql, 0)` directly on all
kinds of dbs.
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