database-partitioning

I know how partitioning in DB2 works but I am unaware about where this partition values exactly get stored. After writing a create partition query, for example: CREATE TABLE orders(id INT, shipdate DATE, …) PARTITION BY RANGE(shipdate) ( STARTING '1/1/2006' ENDING '12/31/2006' EVERY 3 MONTHS ) after running the above query we know that partitions are created on order for every 3 month but when we run a select query the query engine refers this partitions. I am curious to know where this actually get stored, whether in the same table or DB2 has a different table where partition value for every

Why is the table "events_201504" included in the query plan below? Based on my query and the check constraint on that table I would expect the query planner to be able to prune it entirely: database=# \d events_201504 Table "public.events_201504" Column | Type | Modifiers ---------------+-----------------------------+--------------------------------------------------------------- id | bigint | not null default nextval('events_id_seq'::regclass) created_at | timestamp without time zone | Indexes: "events_201504_pkey" PRIMARY KEY, btree (id) "events_201504_created_at" btree (created_at) Check

When partitioning a large table, I have a choice to set the flag -innodb_file_per_table to TRUE or FALSE. True will create many files (one per partition) and greatly increase my disk usage, but allows me to spread partitions on different volumes (which I do not plan to do). FALSE will keep the table as one big file. Assuming I keep all files on the same logical volume, can I expect any significant query performance difference between the two options? Or, more generally, are there any issues to consider when making the choice between the two options besides disk usage and management? Some stats

I would like to avoid Impala nodes unnecessarily requesting data from other nodes over the network in cases when the ideal data locality or layout is known at table creation time. This would be helpful with 'non-additive' operations where all records from a partition are needed at the same place (node) anyway (for ex. percentiles). Is it possible to tell Impala that all data in a partition should always be co-located on a single node for any HDFS replica? In Impala-SQL, I am not sure if the "PARTITIONED BY" clause provide this feature. In my understanding, Impala chunks its partitions into