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sql_column_buffers
Per-column buffer sizes.
Optional, default is empty (deduce the sizes automatically).
Applies to odbc, mssql source types only.
Introduced in version 2.0.1-beta.
ODBC and MS SQL drivers sometimes can not return the maximum
actual column size to be expected. For instance, NVARCHAR(MAX) columns
always report their length as 2147483647 bytes to
indexer even though the actually used length
is likely considerably less. However, the receiving buffers still
need to be allocated upfront, and their sizes have to be determined.
When the driver does not report the column length at all, Sphinx
allocates default 1 KB buffers for each non-char column, and 1 MB
buffers for each char column. Driver-reported column length
also gets clamped by an upper limit of 8 MB, so in case the
driver reports (almost) a 2 GB column length, it will be clamped
and a 8 MB buffer will be allocated instead for that column.
These hard-coded limits can be overridden using the
sql_column_buffers directive, either in order
to save memory on actually shorter columns, or overcome
the 8 MB limit on actually longer columns. The directive values
must be a comma-separated lists of selected column names and sizes:
sql_column_buffers = <colname>=<size>[K|M] [, ...]
Example:
sql_query = SELECT id, mytitle, mycontent FROM documents
sql_column_buffers = mytitle=64K, mycontent=10M
