[GitHub] john-bodley opened a new pull request #4853: [sql] Using read_sql_query instead of read_sql

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john-bodley opened a new pull request #4853: [sql] Using read_sql_query instead of read_sql
URL: https://github.com/apache/incubator-superset/pull/4853
 
 
   The Pandas [read_sql](https://github.com/pandas-dev/pandas/blob/v0.22.0/pandas/io/sql.py#L335-L416) method either reads a SQL query _or_ a database table (we require only the former) into a DataFrame. This results in an additional query (for non-SQLite databases) to determine whether the `sql` object represents a SQL query or table name. This is unnecessary as the `sql` object is always a SQL statement when called from `get_df`. 
   
   This PR uses the [read_sql_query](https://github.com/pandas-dev/pandas/blob/v0.22.0/pandas/io/sql.py#L273-L332) method instead which merely reads the SQL query into a DataFrame thus saving us executing an unnecessary statement.

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