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Simple HTTP-server which works like a proxy for ODBC driver. The main motivation was possible segfaults or another faults in ODBC implementations, which can crash whole clickhouse-server process. This tool works via HTTP, not via pipes, shared memory, or TCP because:
  • It’s simpler to implement
  • It’s simpler to debug
  • jdbc-bridge can be implemented in the same way

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Usage

clickhouse-server use this tool inside odbc table function and StorageODBC. However it can be used as standalone tool from command line with the following parameters in POST-request URL:
  • connection_string — ODBC connection string.
  • sample_block — columns description in ClickHouse NamesAndTypesList format, name in backticks, type as string. Name and type are space separated, rows separated with newline.
  • max_block_size — optional parameter, sets maximum size of single block. Query is send in post body. Response is returned in RowBinary format.

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Example:

$ clickhouse-odbc-bridge --http-port 9018 --daemon

$ curl -d "query=SELECT PageID, ImpID, AdType FROM Keys ORDER BY PageID, ImpID" --data-urlencode "connection_string=DSN=ClickHouse;DATABASE=stat" --data-urlencode "sample_block=columns format version: 1
3 columns:
\`PageID\` String
\`ImpID\` String
\`AdType\` String
"  "http://localhost:9018/" > result.txt

$ cat result.txt
12246623837185725195925621517