[jira] [Updated] (AVRO-1208) Improve Trevni's performance on row-oriented data access

["Yin Huai (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/AVRO-1208?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Yin Huai updated AVRO-1208:
---------------------------

    Attachment: AVRO-1208.1.patch

a initial implementation of the patch. I added two methods in ColumnValues. Users can call startRowWithPrefetch(int numOfPrefetched) to ask Trevni to prefetch n blocks when it needs to read a new block from the disk. Inside of startRowWithPrefetch, startBlockWithPrefetch(int block, int numOfPrefetched) is called to read totally numOfPrefetched+1 blocks.
                
> Improve Trevni's performance on row-oriented data access
> --------------------------------------------------------
>
>                 Key: AVRO-1208
>                 URL: https://issues.apache.org/jira/browse/AVRO-1208
>             Project: Avro
>          Issue Type: Improvement
>    Affects Versions: 1.7.3
>            Reporter: Yin Huai
>         Attachments: AVRO-1208.1.patch
>
>
> Trevni uses an 64KB internal buffer to store values of a column. When accessing a column, it reads 64KB (if we do not consider compression and checksum) data from the storage layer. However, when the table is accessed in a row-oriented fashion (a entire row needs to be handed over to the upper layer), in the worst case (a full table scan and values of this table are all the same size), every 64KB data read can cause a seek.
> This jira is used to discuss if we should consider the data access pattern mentioned above and if so, how to improve the performance of Trevni. Row-oriented data processing engines, e.g. Hive, can benefit from this work.

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