[
https://issues.apache.org/jira/browse/PHOENIX-1333?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14165456#comment-14165456
]
ramkrishna.s.vasudevan commented on PHOENIX-1333:
-------------------------------------------------
bq.I'd keep a running count of the number of bytes and serialize it in the
front of the byte[] and use it for sizing (that plus the writeVInt size of the
count and you should be able to get an exact byte amount.
Which byte[] you mean? The row that is added to the list in the
Pair<Integer,List<byte[]>? If we add it here then we may have not know the
exact length until we traverse the guidePost map.
bq.Make sure when you combine the guideposts for a given family, that you add
the previous guidePostCount and guidePostDepth to the new one here:
So this means I have to have a map that has the guidePostDepth *
guidePosts.size() collected against the family. Every time we access for the
same family get the previous value and add it with the new value - put it back
to the map?
> Store statistics guideposts as VARBINARY
> ----------------------------------------
>
> Key: PHOENIX-1333
> URL: https://issues.apache.org/jira/browse/PHOENIX-1333
> Project: Phoenix
> Issue Type: Sub-task
> Reporter: James Taylor
> Assignee: ramkrishna.s.vasudevan
> Priority: Critical
> Attachments: Phoenix-1333.patch
>
>
> There's a potential problem with storing the guideposts as a VARBINARY ARRAY,
> as pointed out by PHOENIX-1329. We'd run into this issue if we're collecting
> stats for a table with a trailing VARBINARY row key column if the value
> contained embedded null bytes. Because of this, we're better off storing
> guideposts as VARBINARY and serializing/deserializing in the following manner:
> <byte length as vint><bytes><byte length as vint><bytes>...
> We should also store as a separate KeyValue column the total number of
> guideposts. So the schema of SYSTEM.STATS would look like this now instead:
> {code}
> public static final String CREATE_STATS_TABLE_METADATA =
> "CREATE TABLE " + SYSTEM_CATALOG_SCHEMA + ".\"" +
> SYSTEM_STATS_TABLE + "\"(\n" +
> // PK columns
> PHYSICAL_NAME + " VARCHAR NOT NULL," +
> COLUMN_FAMILY + " VARCHAR," +
> REGION_NAME + " VARCHAR," +
> GUIDE_POSTS + " VARBINARY," +
> GUIDE_POSTS_COUNT + " SMALLINT," +
> MIN_KEY + " VARBINARY," +
> MAX_KEY + " VARBINARY," +
> LAST_STATS_UPDATE_TIME+ " DATE, "+
> "CONSTRAINT " + SYSTEM_TABLE_PK_NAME + " PRIMARY KEY ("
> + PHYSICAL_NAME + ","
> + COLUMN_FAMILY + ","+ REGION_NAME+"))\n" +
> // TODO: should we support versioned stats?
> // Install split policy to prevent a physical table's stats from
> being split across regions.
> HTableDescriptor.SPLIT_POLICY + "='" +
> MetaDataSplitPolicy.class.getName() + "'\n";
> {code}
> Then the serialization code in StatisticsTable.addStats() would need to
> change to populate the GUIDE_POSTS_COUNT and serialize the GUIDE_POSTS in the
> new format.
> The deserialization code is isolated to StatisticsUtil.readStatisitics(). It
> would need to read the GUIDE_POSTS_COUNT first for estimated sizing, and then
> deserialize the GUIDE_POSTS in the new format.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
