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Large, persistent DataFrame in pandas
...le paths
in_csv = '../data/my_large.csv'
out_sqlite = '../data/my.sqlite'
table_name = 'my_table' # name for the SQLite database table
chunksize = 100000 # number of lines to process at each iteration
# columns that should be read from the CSV file
columns = ['molecule_id','charge','db','drugsnow'...
Which is faster/best? SELECT * or SELECT column1, colum2, column3, etc
... that SQL Server can access the data from indexes rather than querying the table data.
Here's a post I wrote about it: The real reason select queries are bad index coverage
It's also less fragile to change, since any code that consumes the data will be getting the same data structure regardless...
MySQL select one column DISTINCT, with corresponding other columns
...
try this query
SELECT ID, FirstName, LastName FROM table GROUP BY(FirstName)
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Alternate output format for psql
I am using PostgreSQL 8.4 on Ubuntu. I have a table with columns c1 through cN . The columns are wide enough that selecting all columns causes a row of query results to wrap multiple times. Consequently, the output is hard to read.
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Oracle “Partition By” Keyword
...ment for every employee record. (It is as if you're de-nomalising the emp table; you still return every record in the emp table.)
emp_no dept_no DEPT_COUNT
1 10 3
2 10 3
3 10 3 <- three because there are three "dept_no = 10" records
4 20 2
5 ...
What's the Hi/Lo algorithm?
...re out the next identifier value knowing we use hilo in this particular DB table?
– Vlad Mihalcea
Feb 7 '17 at 1:46
My...
Best way to check if UITableViewCell is completely visible
I have a UITableView with cells of different heights and I need to know when they are completely visible or not.
10 Answe...
Inserting multiple rows in a single SQL query? [duplicate]
I have multiple set of data to insert at once, say 4 rows. My table has three columns: Person , Id and Office .
4 Answe...
How to load a tsv file into a Pandas DataFrame?
...od - it was very slow and failed indexing at the end. Instead, i used read_table(), which worked much faster and without the extra param.
– Yurik
Aug 15 '14 at 9:56
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MySQL - SELECT WHERE field IN (subquery) - Extremely slow why?
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Rewrite the query into this
SELECT st1.*, st2.relevant_field FROM sometable st1
INNER JOIN sometable st2 ON (st1.relevant_field = st2.relevant_field)
GROUP BY st1.id /* list a unique sometable field here*/
HAVING COUNT(*) > 1
I think st2.relevant_field must be in the select, because other...