This documentation is for an unreleased version of Apache Paimon. We recommend you use the latest stable version.
Query Performance #
Data Skipping By Order #
Paimon by default records the maximum and minimum values of each field in the manifest file.
In the query, according to the WHERE
condition of the query, according to the statistics in the manifest do files
filtering, if the filtering effect is good, the query would have been minutes of the query will be accelerated to
milliseconds to complete the execution.
Often the data distribution is not always effective filtering, so if we can sort the data by the field in WHERE
condition?
You can take a look to Flink COMPACT Action or
Flink COMPACT Procedure or Spark COMPACT Procedure.
Data Skipping By File Index #
You can use file index too, it filters files by index on the read side.
CREATE TABLE <PAIMON_TABLE> (<COLUMN> <COLUMN_TYPE> , ...) WITH (
'file-index.bloom-filter.columns' = 'c1,c2',
'file-index.bloom-filter.c1.items' = '200'
);
Define file-index.bloom-filter.columns
, Data file index is an external index file and Paimon will create its corresponding index file for each file. If the index
file is too small, it will be stored directly in the manifest, otherwise in the directory of the data file. Each data file
corresponds to an index file, which has a separate file definition and can contain different types of indexes with
multiple columns.
Different file index may be efficient in different scenario. For example bloom filter may speed up query in point lookup scenario. Using a bitmap may consume more space but can result in greater accuracy.
Bloom Filter
:
file-index.bloom-filter.columns
: specify the columns that need bloom filter index.file-index.bloom-filter.<column_name>.fpp
to config false positive probability.file-index.bloom-filter.<column_name>.items
to config the expected distinct items in one data file.
Bitmap
:
file-index.bitmap.columns
: specify the columns that need bitmap index.
Bit-Slice Index Bitmap
file-index.bsi.columns
: specify the columns that need bsi index.
More filter types will be supported…
If you want to add file index to existing table, without any rewrite, you can use rewrite_file_index
procedure. Before
we use the procedure, you should config appropriate configurations in target table. You can use ALTER clause to config
file-index.<filter-type>.columns
to the table.
How to invoke: see flink procedures