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Posted to dev@datafu.apache.org by "Eyal Allweil (JIRA)" <ji...@apache.org> on 2017/09/12 09:50:00 UTC
[jira] [Updated] (DATAFU-127) New macro - samply by keys
[ https://issues.apache.org/jira/browse/DATAFU-127?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Eyal Allweil updated DATAFU-127:
--------------------------------
Attachment: DATAFU-127.patch
Patch including new macros and tests
> New macro - samply by keys
> --------------------------
>
> Key: DATAFU-127
> URL: https://issues.apache.org/jira/browse/DATAFU-127
> Project: DataFu
> Issue Type: New Feature
> Reporter: Eyal Allweil
> Assignee: Eyal Allweil
> Labels: macro
> Attachments: DATAFU-127.patch
>
>
> Two macros that return a sample of a larger table based on a list of keys, with the schema of the larger table. One of the macros filters by dates, the other doesn't.
> If there are multiple rows with a key that appears in the key list, all of them will be returned (no deduplication is done). The results are returned ordered by the key field in a single file.
> The implementation uses a replicated join for efficiency, but this means the key list shouldn't be too large as to not fit in memory.
> The first macro's definition looks as follows:
> DEFINE sample_by_keys(table, sample_set, join_key_table, join_key_sample) returns out {
> - table_name - table name to sample
> - sample_set - a set of keys
> - join_key_table - join column name in the table
> - join_key_sample - join column name in the sample
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