InvisibleProgrammer commented on code in PR #6577:
URL: https://github.com/apache/hive/pull/6577#discussion_r3543771530
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standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/directsql/MetaStoreDirectSql.java:
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@@ -534,6 +537,151 @@ public void addPartitions(List<MPartition> parts,
List<List<MPartitionPrivilege>
directSqlInsertPart.addPartitions(parts, partPrivilegesList,
partColPrivilegesList);
}
+ /**
+ * Gets a suitable column descriptor for an existing table, based on the
latest partitions
+ *
+ * @param cols column list of a partition
+ * @param tblId table id
+ * @return an existing column descriptor which columns matches with @cols.
Null if there is no match.
+ * @throws MetaException
+ */
+ public MColumnDescriptor getColumnDescriptor(List<FieldSchema> cols, long
tblId)
+ throws MetaException {
+
+ if (cols == null || cols.isEmpty()) {
+ return null;
+ }
+
+ // Please note! In case you modify any of those methods, run
TestHMSColumnDescriptorReuse with all the supported databases
+ List<Long> cdCandidates = findTheLatestColumnDescriptors(tblId);
+
+ cdCandidates = filterCandidatesByColumnCount(cdCandidates, cols.size());
+
+ Long matchedColumnDescriptorId =
matchColumnDescriptorWithActualColumns(cdCandidates, cols);
+
+ if (matchedColumnDescriptorId != null) {
+ return pm.getObjectById(MColumnDescriptor.class,
matchedColumnDescriptorId);
+ }
+
+ return null;
+ }
+
+ private @Nullable List<Long> findTheLatestColumnDescriptors(long tblId)
throws MetaException {
+ Query<?> query = null;
+ try {
+ String findLatestDescriptorsSql = """
+ SELECT s."CD_ID"
+ FROM "PARTITIONS" p
+ JOIN "SDS" s ON s."SD_ID" = p."SD_ID"
+ WHERE p."TBL_ID" = ?
+ GROUP BY s."CD_ID"
+ ORDER BY MAX(p."PART_ID") DESC
Review Comment:
I cannot add a limit clause that is compatible with all the supported
databases. However, I can add a limit to the executeWithArray call so that it
will only read the first 20 records.
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