56 lines
1.6 KiB
Markdown
56 lines
1.6 KiB
Markdown
# sqlite-parquet-vtable
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A SQLite [virtual table](https://sqlite.org/vtab.html) extension to expose Parquet files as SQL tables.
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## Caveats
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I'm not an experienced C/C++ programmer. This library is definitely not bombproof. It's good enough for my use case,
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and may be good enough for yours, too.
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* I don't use `sqlite3_malloc` and `sqlite3_free` for C++ objects
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* Maybe this doesn't matter, since portability isn't a goal
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* The C -> C++ interop definitely leaks some C++ exceptions
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* Obvious cases like file not found and unsupported Parquet types are OK
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* Low memory conditions aren't handled gracefully.
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## Building
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1. Install [`parquet-cpp`](https://github.com/apache/parquet-cpp)
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1. Master appears to be broken for text row group stats; see https://github.com/cldellow/sqlite-parquet-vtable/issues/5 for which versions to use
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2. Run `./build-sqlite` to fetch and build the SQLite dev bits
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3. Run `./parquet/make` to build the module
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1. You will need to fixup the paths in this file to point at your local parquet-cpp folder.
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## Use
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```
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$ sqlite/sqlite3
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sqlite> .load parquet/libparquet
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sqlite> CREATE VIRTUAL TABLE demo USING parquet('parquet-generator/100-rows-1.parquet');
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sqlite> SELECT * FROM demo;
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...if all goes well, you'll see data here!...
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```
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## Supported features
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### Index
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Only full table scans are supported.
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### Types
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These types are supported:
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* INT96 timestamps (exposed as milliseconds since the epoch)
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* INT8/INT16/INT32/INT64
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* UTF8 strings
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* BOOLEAN
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* FLOAT
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* DOUBLE
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* Variable- and fixed-length byte arrays
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These are not supported:
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* UINT8/UINT16/UINT32/UINT64
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* DECIMAL
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