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https://issues.apache.org/jira/browse/HIVE-24663?focusedWorklogId=599891&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-599891
]
ASF GitHub Bot logged work on HIVE-24663:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 20/May/21 15:52
Start Date: 20/May/21 15:52
Worklog Time Spent: 10m
Work Description: deniskuzZ commented on a change in pull request #2266:
URL: https://github.com/apache/hive/pull/2266#discussion_r636228265
##########
File path:
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/txn/TxnHandler.java
##########
@@ -5390,6 +5406,493 @@ public void countOpenTxns() throws MetaException {
}
}
+ private void cleanOldStatsFromPartColStatTable(Map<String, PartitionInfo>
statsPartInfoMap,
+ Map<String, ColumnStatistics>
newStatsMap,
+ Connection dbConn) throws
SQLException {
+ PreparedStatement statementDelete = null;
+ int numRows = 0;
+ int maxNumRows = MetastoreConf.getIntVar(conf,
ConfVars.DIRECT_SQL_MAX_ELEMENTS_VALUES_CLAUSE);
+ String delete = "DELETE FROM \"PART_COL_STATS\" where \"PART_ID\" = ? AND
\"COLUMN_NAME\" = ?";
+
+ try {
+ statementDelete = dbConn.prepareStatement(delete);
+ for (Map.Entry entry : newStatsMap.entrySet()) {
+ // If the partition does not exist (deleted/removed by some other
task), no need to update the stats.
+ if (!statsPartInfoMap.containsKey(entry.getKey())) {
+ continue;
+ }
+
+ ColumnStatistics colStats = (ColumnStatistics) entry.getValue();
+ for (ColumnStatisticsObj statisticsObj : colStats.getStatsObj()) {
+ statementDelete.setLong(1,
statsPartInfoMap.get(entry.getKey()).partitionId);
+ statementDelete.setString(2, statisticsObj.getColName());
+ numRows++;
+ statementDelete.addBatch();
+ if (numRows == maxNumRows) {
+ statementDelete.executeBatch();
+ numRows = 0;
+ LOG.info("Executed delete " + delete + " for numRows " + numRows);
+ }
+ }
+ }
+
+ if (numRows != 0) {
+ statementDelete.executeBatch();
+ }
+ } finally {
+ closeStmt(statementDelete);
+ }
+ }
+
+ private long getMaxCSId(Connection dbConn) throws SQLException {
+ Statement stmtInt = null;
+ ResultSet rsInt = null;
+ long maxCsId = 0;
+ try {
+ stmtInt = dbConn.createStatement();
+ while (maxCsId == 0) {
+ String query = "SELECT \"NEXT_VAL\" FROM \"SEQUENCE_TABLE\" WHERE
\"SEQUENCE_NAME\"= "
Review comment:
that would create lock on SEQUENCE_TABLE for the duration of the whole
stats update operation. Won't it interfere with the regular flow?
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Issue Time Tracking
-------------------
Worklog Id: (was: 599891)
Time Spent: 0.5h (was: 20m)
> Batch process in ColStatsProcessor for partitions.
> --------------------------------------------------
>
> Key: HIVE-24663
> URL: https://issues.apache.org/jira/browse/HIVE-24663
> Project: Hive
> Issue Type: Improvement
> Reporter: Rajesh Balamohan
> Assignee: mahesh kumar behera
> Priority: Major
> Labels: performance, pull-request-available
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> When large number of partitions (>20K) are processed, ColStatsProcessor runs
> into DB issues.
> {{ db.setPartitionColumnStatistics(request);}} gets stuck for hours together
> and in some cases postgres stops processing.
> It would be good to introduce small batches for stats gathering in
> ColStatsProcessor instead of bulk update.
> Ref:
> https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/stats/ColStatsProcessor.java#L181
> https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/stats/ColStatsProcessor.java#L199
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