Eyal Allweil created DATAFU-127:
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Summary: 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
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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