Implementing the per-query statistics log

The EQL per-query statistics log is turned off by default.

You can specify its creation by using the dgraph --log_stats flag: 

--log_stats path

The path argument sets the path and filename for the log.

This argument must be a filename, not a directory. If the file cannot be opened, no logging will be performed. The log file uses an XML format, as shown in the following example that shows a log entry for this simple query: 

fn:collection()/record[author_nationality = "english"]

To read the file, you can open it with a text editor, such as TextPad. 

<?xml version="1.0" encoding="UTF-8"?>
<Queries>
<Query xmlns="endeca:stats">

  <EndecaQueryLanguage>
    <Stats>
      <RecordPath query_string="fn:collection()/record[author_nationality = &quot;english&quot;]">
        <StatInfo number_of_records="2">
          <TimeInfo>
            <Descendant unit="ms">0.47705078125</Descendant>
            <Self unit="ms">0.194580078125</Self>
            <Total unit="ms">0.671630859375</Total>
          </TimeInfo>
        </StatInfo>
        <Predicate query_string="[author_nationality = &quot;english&quot;]">
          <StatInfo number_of_records="2">
            <TimeInfo>
              <Descendant unit="ms">0.287841796875</Descendant>
              <Self unit="ms">0.189208984375</Self>
              <Total unit="ms">0.47705078125</Total>
            </TimeInfo>
          </StatInfo>
          <PropertyComparison query_string="author_nationality = &quot;english&quot;">
            <StatInfo number_of_records="2">
              <TimeInfo>
                <Descendant unit="ms">0.001953125</Descendant>
                <Self unit="ms">0.285888671875</Self>
                <Total unit="ms">0.287841796875</Total>
              </TimeInfo>
            </StatInfo>
            <StringLiteral query_string="&quot;english&quot;">
              <StatInfo number_of_records="0">
                <TimeInfo>
                  <Descendant unit="ms">0</Descendant>
                  <Self unit="ms">0.001953125</Self>
                  <Total unit="ms">0.001953125</Total>
                </TimeInfo>
              </StatInfo>
            </StringLiteral>
          </PropertyComparison>
        </Predicate>
      </RecordPath>
    </Stats>
  </EndecaQueryLanguage>

</Query>
</Queries>

The following table describes the meanings of the elements and attributes.

Element/Attribute

Description

Query

Encapsulates the statistics for a given query (that is, each query will have its own Query node).

RecordPath

The record path of a collection() function.

Predicate

Lists the time spent processing the predicate part of a query.

otherNodes

Lists the time spent processing an expression part of an query, such as PropertyComparison (property or range filter query), StringLiteral (property value query), MatchesExpr (text search query), and DValComparison (dimension value query).

query_string

For RecordPath, this attribute lists the full query that was issued. For the other elements, it lists the part of the query for which statistics in that element are given.

number_of_records

Returns the number of records which satisfy the query_string in a given node.

StatInfo

Encapsulates the TimeInfo and CacheInfo information.

TimeInfo

Encapsulates time-related information about the node.

Descendant

The time, in milliseconds, spent in the descendants of a given node.

Self

The total amount of time, in milliseconds, spent in this node.

Total

The total amount of time, in milliseconds, spent in this node and its descendants.

CacheInfo

Encapsulates information about cache hits, misses, and insertions. Cache is checked only when a combined relationship filter and range comparison is made.

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