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PERF: Only do case sensitive check when not lower case #12880

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PERF: Only do case sensitive check when not lower case #12880

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Only do case sensitive check when not lower case
Apr 12, 2016
fda61d4
Update docs
Apr 12, 2016
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v0.18.1.txt
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Expand Up @@ -203,6 +203,7 @@ Performance Improvements



- Improved performance of ``DataFrame.to_sql`` when checking case sensitivity. Now only checks if table has been created correctly when table name is not lower case. (:issue:`12876`)
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case sensitivity for tables.




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30 changes: 17 additions & 13 deletions pandas/io/sql.py
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Expand Up @@ -1248,19 +1248,23 @@ def to_sql(self, frame, name, if_exists='fail', index=True,
schema=schema, dtype=dtype)
table.create()
table.insert(chunksize)
# check for potentially case sensitivity issues (GH7815)
engine = self.connectable.engine
with self.connectable.connect() as conn:
table_names = engine.table_names(
schema=schema or self.meta.schema,
connection=conn,
)
if name not in table_names:
warnings.warn("The provided table name '{0}' is not found exactly "
"as such in the database after writing the table, "
"possibly due to case sensitivity issues. Consider "
"using lower case table names.".format(name),
UserWarning)
if (not name.isdigit() and not name.islower()):
# check for potentially case sensitivity issues (GH7815)
# Only check when name is not a number and name is not lower case
engine = self.connectable.engine
with self.connectable.connect() as conn:
table_names = engine.table_names(
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can you give some tests for this (and for the warning).

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Sure will do

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@jreback Apparently the warning itself can't be tested
https://github.com/pydata/pandas/blob/master/pandas/io/tests/test_sql.py#L919
I can add a test to ensure the warning is not triggered when using a number as a table name though?

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hmm @jorisvandenbossche

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Well, I indeed put a comment here a while ago that I couldn't test it .. :-)
And I still think this is the case, as we would have to change the settings of the postgresql table on travis (to have this situation occurring), and not sure how to do this/if this is worth the trouble

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To conclude: I think it is OK to merge this without an explicit test

schema=schema or self.meta.schema,
connection=conn,
)
if name not in table_names:
msg = (
"The provided table name '{0}' is not found exactly as "
"such in the database after writing the table, possibly "
"due to case sensitivity issues. Consider using lower "
"case table names."
).format(name)
warnings.warn(msg, UserWarning)

@property
def tables(self):
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