Join metadata helps you understand how your data intersects, including information about matching (common) and non-matching data rows and values within or across data sources. Reviewing join metadata gives you insight into possible issues that might arise when you attempt to join data in your environment. You can perform "what if" scenarios on selected files/tables that could participate in a join or merge. Joins can be examined by looking at the degree (percent) to which the two sets of data joined, the cardinality of the join, and the non-joining (non-matching) rows. For example, you can isolate issues related to duplicate or orphaned (non-matching) records (rows), allowing you to design error handling procedures before merging your data.
See Join Metadata for descriptions of join metadata.
To open join metadata from a data source
- Open a data source.
- Click Summary. The Relationships table shows the number of permanent and discovered keys, dependencies, and joins in the data.
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To view join metadata:
- If one or more joins are permanent or discovered, click the Joins column name. The Joins tab opens showing all permanent and discovered joins associated with the data source. Each row shows the values for the associated metadata. The Venn Diagram for the first join on the Joins tab also opens (replacing the Data Source: Name panel).
- To open a tab showing just those joins that are permanent or discovered, do one of the following:
- Click the number in the Joins column. If there are no joins available, a zero (0) displays and the drill-downs are unavailable.
- From the data source's Source Metadata tab, double-click the Permanent Joins or Discovered Joins row. The Venn Diagram for the first join on the Permanent Joins or Discovered Joins tab also opens (replacing the Data Source: Name panel).
- Optional: From the Joins tab, perform the following tasks:
- Click the Metadata: Selected Join tab to see more information about the join. From this tab, drill downs are available to data rows and values associated with the join. See Viewing Join Rows and Values.
Open join metadata from Join Analyses results
To open join metadata from Join Analyses results
- On the navigation menu, click Data Discovery > View Joins.
- Run a search to find the join analysis you want to view. See Searching Joins.
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On the Join Analyses tab in the search results view, double-click a row. The
Joins and Metadata: Selected Join tabs open. The Joins tab shows all permanent and
discovered joins in the analysis. Each row shows the values for the associated
metadata.
Note: If there are no joins in the analysis, no drill-downs are available. When you hover your cursor over a row, the tool tip No joins found displays when the analysis contains no joins.
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Click the Metadata: Selected Join tab to see more information about the
join. From this tab, drill downs are available to data rows and values associated
with the join. See Viewing Join Rows and Values.
Join Metadata
When you view and export joins, the following metadata columns display. A subset of columns are hidden. To show all columns, see Choosing Columns for View.
Join Metadata
Description
Join Intersection
Color-coded bar representing the three sections of the join's Venn Diagram. Hover over the bar to see the number of any matching, left-hand non-matching, and right-hand non-matching values and rows in the join.
Status
Indicates whether the join is discovered or permanent.
Left Entity Left-hand (LH) entity (data source). Left Expression Expression of LH attributes comprising the LH side of the compound join. Right Entity Right-hand (RH) entity (data source).
Right Expression Expression of RH attributes comprising the RH side of the compound join. Matching Values The number of unique joined values. These are values the left and right side of the join have in common. Inner-Joined Rows The number of matching rows in the inner join; joining rows only. Outer-Joined Rows The number of rows in the outer join; joining rows and non-joining rows from both sides. Left Non-Matching Values The number of unique values on the LH side that did not join. Left Non-Matching Rows The number of rows on the LH side that did not join. Left Outer-Joined Rows The number of rows in the left outer join; joining rows and non-joining left rows. Right Non-Matching Values The number of unique values on the RH side that did not join. Right Non-Matching Rows The number of rows on the RH side that did not join. Right Outer-Joined rows The number of rows in the right outer join; joining rows and non-joining right rows. Left Loaded Rows Number of rows in the LH data source. Left Filter The filter used to select the rows from the LH data source. Left Selected Rows The number of rows selected by the LH filter (or loaded rows if not filtered). Right Loaded Rows Number of rows in the RH data source. Right Filter The filter used to select the rows from the RH data source. Right Selected Rows The number of rows selected by the RH filter (or loaded rows if not filtered). Join Type Indicates whether the join used original values or a standardized, metaphone, or pattern function. Actual Cardinality The actual cardinality of the join. Inferred Cardinality The inferred cardinality of the join. Exact Cardinality The exact cardinality of the join. This is defined as the ratio left cardinality : right cardinality. Best Match Percent The percentage match of the join. Best match of values, LH rows, and RH rows. Percent Matching Values Percentage of values that joined. Percent Left Matching Rows Percentage of left-hand rows that joined. Percent Right Matching Rows Percentage of right-hand rows that joined. Left Join Rows The number of rows from the LH side that joined. Left Join Cardinality The cardinality of the joined values from the LH side of the join. On average, each joining value occurs this number of times on the LH side. Right Join Rows The number of rows from the RH side that joined. Right Join Cardinality The cardinality of the joined values from the RH side of the join. On average, each joining value occurs this number of times on the RH side. Analyzed Date The date the join was analyzed. Analyzed By The user who analyzed the data. Created By The user who created the join. Created Date The date the join was created. Performed By User who created the join result index. Performed Date The date the join result index was created. Edited By The user who edited the join definition. Edited Date The date the join was edited. Note Count The number of notes for this join. Join Job The name of the join analysis job upon creation. Join Result Segment Whether the result is the natural (inner) join or an outer (full, LH side, or RH side) join. Left Non-Matching Row Action The documented left non-matching row action; for example, accept, ignore, reject, or warning. Right Non-Matching Row Action The documented right non-matching row action; for example, accept, ignore, reject, or warning.