54 lines
1.5 KiB
Markdown
54 lines
1.5 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 a professional C/C++ programmer. These are the caveats I'm aware of, but there are probably others:
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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 (SQLite API implementation) -> C++ interop (to talk to parquet-cpp) probably leaks some C++ exceptions
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* Your process may crash due to my error. Sorry!
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* I handle the obvious cases like file not found and unsupported Parquet types but I suspect 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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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('demo.parquet');
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sqlite> select * from demo limit 1;
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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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These are not supported:
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* UINT8/UINT16/UINT32/UINT64
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* Fixed length byte arrays, including JSON and BSON subtypes
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* DECIMAL
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