Bulk and ad-hoc parquet export APIs

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Needs clarification
Activity status
Stale
Tech stack
sql
Domain
api, database

Research direction

Start by reviewing the existing table-partition-to-Parquet export path, then compare the requested SQL COPY ... TO ... WITH FORMAT PARQUET and /exp?query=...&format=parquet entry points. The work is complete when both bulk and ad-hoc exports support the stated Parquet options and produce downloadable, chronologically ordered files without using the WAL.

Written by the indexing model from the issue text.

Description

compatibility open format open source QoL SQL storage

Currently, Parquet files can be exported from QuestDB by converting a table's partitions to Parquet format, and copying them out. This goes via the WAL, so can impact ingestion performance.

Instead, we will add two more means to export data in parquet format:

  • bulk export: COPY ... TO ... WITH FORMAT PARQUET;
    • This supports exporting a table or arbitrary query to parquet
    • The parquet format can be configured (row group sizes, compression codecs)
    • The data can be newly partitioned
  • ad-hoc export: /exp?query=...&format=parquet
    • This is similar to the above option, but works via the REST API
    • This allows you to download smaller datasets in parquet format, instead of CSV.

Chronologically-ordered parquet files can be ingested very quickly into QuestDB. This feature will make it much simpler to get data in and out of the database, and hook it up to other tools such as Pandas/Polars/DuckDB.

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7
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0
PR merge metrics
No merged PRs in 30d

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