Support custom metadata for schema and columns #20
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Closes #13. This PR adds two new functions: `Arrow.getmetadata(x)` and `Arrow.setmetadata!(x, ::Dict{String, String})`, which allows, rather obviously, setting metadata for an arbitrary object and then retrieving that metadata. By utilizing these functions, users can get/set custom metadata that is serialized in the arrow format at the schema level and field (column) level. More specifically, to set arrow schema custom metadata, a user would call `Arrow.setmetadata!(tbl, meta)` on their table object `tbl`. To retrive arrow schema custom metadata, one can call `tbl = Arrow.Table(...); meta = Arrow.getmetadata(tbl)`. Similarly for column/field-level metadata, one can call `Arrow.setmetadata!(col, colmeta)` to cause custom metadata to be serialized in the arrow message, and call `Arrow.getmetadata(tbl.colX)` to retrive custom metadata for a specific column in an `Arrow.Table`. Note that technically the arrow `Message` and `Footer` objects also allow setting custom metadata, but those are not addressed at all in this PR since they seem to be less useful/urgent.
Codecov Report
@@ Coverage Diff @@
## master #20 +/- ##
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+ Coverage 79.26% 79.95% +0.68%
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Files 13 13
Lines 1992 2020 +28
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+ Hits 1579 1615 +36
+ Misses 413 405 -8
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quinnj
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Oct 3, 2020
Closes #13. This PR adds two new functions: `Arrow.getmetadata(x)` and `Arrow.setmetadata!(x, ::Dict{String, String})`, which allows, rather obviously, setting metadata for an arbitrary object and then retrieving that metadata. By utilizing these functions, users can get/set custom metadata that is serialized in the arrow format at the schema level and field (column) level. More specifically, to set arrow schema custom metadata, a user would call `Arrow.setmetadata!(tbl, meta)` on their table object `tbl`. To retrive arrow schema custom metadata, one can call `tbl = Arrow.Table(...); meta = Arrow.getmetadata(tbl)`. Similarly for column/field-level metadata, one can call `Arrow.setmetadata!(col, colmeta)` to cause custom metadata to be serialized in the arrow message, and call `Arrow.getmetadata(tbl.colX)` to retrive custom metadata for a specific column in an `Arrow.Table`. Note that technically the arrow `Message` and `Footer` objects also allow setting custom metadata, but those are not addressed at all in this PR since they seem to be less useful/urgent.
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Closes #13. This PR adds two new functions:
Arrow.getmetadata(x)andArrow.setmetadata!(x, ::Dict{String, String}), which allows, ratherobviously, setting metadata for an arbitrary object and then retrieving
that metadata. By utilizing these functions, users can get/set custom
metadata that is serialized in the arrow format at the schema level and
field (column) level. More specifically, to set arrow schema custom
metadata, a user would call
Arrow.setmetadata!(tbl, meta)on theirtable object
tbl. To retrive arrow schema custom metadata, one cancall
tbl = Arrow.Table(...); meta = Arrow.getmetadata(tbl). Similarlyfor column/field-level metadata, one can call
Arrow.setmetadata!(col, colmeta)to cause custom metadata to be serialized in the arrowmessage, and call
Arrow.getmetadata(tbl.colX)to retrive custommetadata for a specific column in an
Arrow.Table.Note that technically the arrow
MessageandFooterobjects alsoallow setting custom metadata, but those are not addressed at all in
this PR since they seem to be less useful/urgent.