update the words
Project: http://git-wip-us.apache.org/repos/asf/trafodion/repo Commit: http://git-wip-us.apache.org/repos/asf/trafodion/commit/84a30a5d Tree: http://git-wip-us.apache.org/repos/asf/trafodion/tree/84a30a5d Diff: http://git-wip-us.apache.org/repos/asf/trafodion/diff/84a30a5d Branch: refs/heads/master Commit: 84a30a5d7cce5e94da7c433711a54e434844236e Parents: f117f0d Author: Liu Ming <[email protected]> Authored: Sat Sep 22 15:26:55 2018 +0000 Committer: Liu Ming <[email protected]> Committed: Sat Sep 22 15:26:55 2018 +0000 ---------------------------------------------------------------------- .../src/asciidoc/_chapters/query_execution.adoc | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/trafodion/blob/84a30a5d/docs/cqd_reference/src/asciidoc/_chapters/query_execution.adoc ---------------------------------------------------------------------- diff --git a/docs/cqd_reference/src/asciidoc/_chapters/query_execution.adoc b/docs/cqd_reference/src/asciidoc/_chapters/query_execution.adoc index ca5815b..3391fed 100644 --- a/docs/cqd_reference/src/asciidoc/_chapters/query_execution.adoc +++ b/docs/cqd_reference/src/asciidoc/_chapters/query_execution.adoc @@ -296,18 +296,18 @@ More disk space can process larger data sets. [cols="25%h,75%"] |=== -| *Description* | Set the max retry time when concurrent processes conflict to get next sequence range from system table. +| *Description* | Set the max retry time when concurrent processes try to get next sequence conflict | *Values* | Numeric value. The default value is *'100'*. | *Usage* a| -When multiple clients try to do next operation on a same sequence, if cache runs out, all of the clients try to get the next range and go into race. So one may get a range that another client already got. This is concurrency control, Trafodion is using a retry logic to do the control. -After the SQL engine gets the next range from system metadata table, it will check the updated timestamp, if it is same as the timestampt set by itself, then it is successful. Otherwise, the range is obtained by some other concurrent clients. Then the engine wait and retry. +Multiple clients try to do NEXT operation on a same sequence, when cache runs out, all of the clients try to get the next range and go into race. So one client may get a range that another client already got. So Trafodion needs to do concurrent control in this case. +After the SQL engine gets the next range from system metadata table, it will set an upate timestamp. Each time it get the next range, it will check the updated timestamp, if it is same as the timestampt set by itself, then it is successful. Otherwise, the range is obtained by some other concurrent clients. Then the engine wait and retry. -When concurrency conflict is very high, for example a query with high DOP and processing billions of rows, it is possible to fail due to run out of retry time. In that case, user will get ERROR 1583. +When concurrency conflict is very high, for example a query is running with high DOP and processing billions of rows, it is possible to fail due to run out of retry time. In that case, user will get SQL ERROR-1583. -This CQD is to control the retry number. It is set to 100 by default. When specific query using sequence run into ERROR 1583, one can increase this CQD to allow SQL engine to retry for more times, and avoid the 1583 issue. +This CQD is to set the retry number. It is set to 100 by default. When specific query using sequence run into SQL ERROR-1583, one can increase this CQD to allow SQL engine to retry for more times, and avoid the SQL ERROR-1583. | *Production Usage* | Please contact {project-support}. | *Impact* |
