Best Practices

Importance of Using Stream Name with Copy


When using a COPY bulk load in Vertica, it’s important to properly identify the load using the optional STREAM NAME parameter. This parameter makes it possible to easily identify loads when monitoring system load streams since they can generally be resource intensive.

For basic query monitoring, I reference the query_requests system table under the V_MONITOR schema. When I was examining the columns, I stumbled upon request_label. This seemed like it could be a really useful resource when it comes to identifying queries and monitoring system resources.

The way I read the documentation is if this parameter is not set, Vertica will try to name the stream (I have yet to see):

By default, HP Vertica names streams by table and file name. For example, if you have two files (f1, f2) in Table A, their stream names are A-f1, A-f2, respectively.

In order to manually set the STREAM NAME parameter, it just needs to be supplied with the COPY statement:

The stream name will appear in the load_streams and query_requests system tables under stream_name and request_label columns respectively. While the documentation suggests that load_streams maintains historical load metrics, I haven’t found this to be the case. I only seem to find the active load metrics, and per the documentation, there’s no way to increase the retention parameters on this system table.


About the author / 

Norbert Krupa

Norbert is the founder of and a Solutions Engineer at Talend. He is an HP Accredited Solutions Expert for Vertica Big Data Solutions. He has written the Vertica Diagnostic Queries which aim to cover monitoring, diagnostics and performance tuning. The views, opinions, and thoughts expressed here do not represent those of the user's employer.

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