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From DaveBirdsall <...@git.apache.org>
Subject [GitHub] incubator-trafodion pull request: Trafodion 1851: Publication of n...
Date Tue, 15 Mar 2016 16:42:38 GMT
Github user DaveBirdsall commented on a diff in the pull request:

    https://github.com/apache/incubator-trafodion/pull/379#discussion_r56196654
  
    --- Diff: docs/cqd_reference/src/asciidoc/_chapters/operational_controls.adoc ---
    @@ -53,12 +53,89 @@ then a large number of queries may be impacted. Therefore, you need
to assess if
     |===
     
     <<<
    +[[explain-description-column-size]]
    +== EXPLAIN_DESCRIPTION_COLUMN_SIZE
    +
    +[cols="25%h,75%"]
    +|===
    +| *Description*               | Specifies maximum length of DESCRIPTION column for EXPLAIN
virtual tables.
    +| *Values*                    |
    +Positive integer > 10,000 +
    + +
    +Default: -1, indicating a maximum size of 10,000.
    +| *Usage*                     | Query-plan information for a SQL DML statement is stored
temporarily in the Explain virtual table. 
    +For large queries or queries with complex predicates, the default size of 10 KB may be
insufficient to describe certain nodes in the query plan. 
    +Specifying a larger value for this CQD allows more bytes to be stored in the description
column. +
    + +
    +Change this setting if you see explain plan being undesirably truncated only.
    +| *Production Usage*          | Yes.
    +| *Impact*                    | The explain plan truncation is reduced or removed.
    +| *Level*                     | System.
    +| *Conflicts/Synergies*       | Not applicable.
    +| *Real Problem Addressed*    | Not applicable.
    +| *Introduced In Release*     | Trafodion 1.3.0.
    +| *Deprecated In Release*     | Not applicable.
    +|===
    +
    +<<<
    +[[hbase-region-server-max-heap-size]]
    +== HBASE_REGION_SERVER_MAX_HEAP_SIZE
    +
    +[cols="25%h,75%"]
    +|===
    +| *Description*               | Enables Trafodion to use HBase block cache in an optimal
manner.  Defines the maximum Java
    +heap size (-Xmx option) the HBase Region Server are assigned, in MB units.
    +| *Values*                    |
    +Positive integer. +
    + +
    +Default: *'1024'*.
    +| *Usage*                     | If the HBase Region servers are configured with a maximum
Java heap size different than 1 GB, then
    +set this attribute so that Trafodion is aware of the actual maximum heap size of the
Region Servers.
    +| *Production Usage*          | Yes.
    +| *Impact*                    | When set correctly, this CQD ensures that HBase block
cache are be used optimally. Small scans
    +are cached and larger scans are not cached to avoid cache trashing.
    +| *Level*                     | System.
    +| *Conflicts/Synergies*       | Not applicable.
    +| *Real Problem Addressed*    | Not applicable.
    +| *Introduced In Release*     | Trafodion 1.3.0.
    +| *Deprecated In Release*     | Not applicable.
    +|===
    +
    +<<<
    +[[hive-metadata-refresh-interval]]
    +== HIVE_METADATA_REFRESH_INTERVAL
    +
    +[cols="25%h,75%"]
    +|===
    +| *Description*               | Controls the metadata cache for Hive tables.
    +| *Values*                    | 
    +*-1*: Never invalidate any cache entries. +
    +*0*: Always check the latest meta-data from Hive. +
    +*> 0*: The cached Hive meta-data is valid only for <value> seconds. +
    + +
    +Default: *'0'*.
    +| *Usage*                     | Use of value -1 when the Hive tables are read-only and
no updates are possible to avoid reading the
    +Hive metadata when the same table is referenced in queries again. +
    + +
    +Use of value 0 when frequent update of Hive tables are possible. +
    --- End diff --
    
    Suggested wordsmith: Use a value of 0 when updates to the Hive tables are possible or
likely.


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