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From James Fang <jfang...@ucr.edu>
Subject Postgres Aggregation Function - Discussion
Date Mon, 09 Nov 2015 22:11:31 GMT
The following functions that I am asking about are from
http://www.postgresql.org/docs/9.4/static/functions-aggregate.html

The following google doc contains a spreadsheet of all the current
aggregation functions that exist in AQL and SQL. The colored portions will
be the portions that I wish to discuss. I assumed that AQL returns null if
at least 1 of the results in the aggregation is null while SQL ignores the
tuple if it is null.
https://docs.google.com/document/d/1l9QtRAB7H3yzP3976livpKzJZHVJlPdvDrjlm2YCsM0/edit?usp=sharing

Questions:
1) Do we need array_agg, this function just groups up the results together
into one array as output. If so, do we want a scalar version or aggregate
version?
2) For bitwise-or and bitwise-and, I have implemented a sql aggregate
version. Do we want a AQL aggregate version as well? Do you think that we
should implement this as a scalar or as an aggregation?
3) For boolean-or and boolean and, we current have an existing scalar
version for AQL. Do we need a scalar version for SQL? Should we implement a
aggregate version of these boolean functions?
4) Do we need a json_agg function? I do not think so because all the data
is returned in json format. If you have a different answer, let me know.
5) For string_agg, we currently have a scalar version for AQL known as
string-join. Do we need a SQL version?

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