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Important

Helios features are now enabled during weekly update windows and are no longer directly tied to SingleStore engine releases. Refer to the release notes to view the latest features available in your Helios cluster.

MV_QUERY_PROSPECTIVE_HISTOGRAMS

This view contains information about columns which were used in queries where a histogram could have been utilized, but did not have histograms.

This is similar to MV_PROSPECTIVE_HISTOGRAMS, but MV_QUERY_PROSPECTIVE_HISTOGRAMS displays one row per column per query, while MV_PROSPECTIVE_HISTOGRAMS displays one row per column, and aggregates over all queries.

This view counts over all queries (rows) in the in-memory plancache in order to distinguish which of these contain applicable columns. This can be useful for examining which columns included in these queries should have autostats enabled for the future. See further information about this, and how to set autostats in Statistics and Sampling.

Column Name

Description

ACTIVITY_NAME

The ID of the query.

DATABASE_NAME

The name of the related database.

TABLE_NAME

The name of the related table.

COLUMN_NAME

The name of a given column for which a prospective histogram has been identified.

JSON_KEY

When there is a histogram on a json_key as part of a json column, there's an entry here for each (column, json_key) pair. For non-json columns JSON_KEY is NULL.

USAGE_COUNT

The number of times the column was used where a histogram could have been utilized, counting once per occurrence of the table in the query.

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Verification instructions

Note: You must install cosign to verify the authenticity of the SingleStore file.

Use the following steps to verify the authenticity of singlestoredb-server, singlestoredb-toolbox, singlestoredb-studio, and singlestore-client SingleStore files that have been downloaded.

You may perform the following steps on any computer that can run cosign, such as the main deployment host of the cluster.

  1. (Optional) Run the following command to view the associated signature files.

    curl undefined

  2. Download the signature file from the SingleStore release server.

    • Option 1: Click the Download Signature button next to the SingleStore file.

    • Option 2: Copy and paste the following URL into the address bar of your browser and save the signature file.

    • Option 3: Run the following command to download the signature file.

      curl -O undefined

  3. After the signature file has been downloaded, run the following command to verify the authenticity of the SingleStore file.

    echo -n undefined |
        cosign verify-blob --certificate-oidc-issuer https://oidc.eks.us-east-1.amazonaws.com/id/CCDCDBA1379A5596AB5B2E46DCA385BC \
          --certificate-identity https://kubernetes.io/namespaces/freya-production/serviceaccounts/job-worker \
          --bundle undefined \
          --new-bundle-format -
    Verified OK

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