Adds support for ZSTD encoding in schema-ddl #262
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@miike has signed the Software Grant and Corporate Contributor License Agreement |
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Thanks @chuwy! |
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Cherry-picked to #309, closing. |
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This PR adds support for ZSTD encoding (#237)
The first commit modifies the default for VARCHAR (and TIMESTAMP) columns to preferentially now use ZSTD over LZO for these column types. It doesn't yet override suggestions for other data types though this would likely be useful. I'm not sure if this is something we'd like to test before going down this route (e.g., how well ZSTD functions on INTs that are uniformly distributed, normally distributed etc).
The second commit modifies the encodings on the self and parent columns from RUNLENGTH to ZSTD. For columns that primarily contain one value (such as
schema_vendor) this change makes little difference to space on disk but for other columns, such asschema_versionthis can make a significant difference. In a small sample of ~10 million rows if two schemas are in use simultaneously and we make the assumption that the schema used is independent and identically distributed (over time) this column is approximated 2/3 of the size on disk using ZSTD when compared to RUNLENGTH.