[oracle] Missing total.bytes field in tablespace datastream #39787
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@@ -11,31 +11,24 @@ import ( | |
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| type tempFreeSpace struct { | ||
| TablespaceName string | ||
| TotalSpaceBytes sql.NullInt64 | ||
| UsedSpaceBytes sql.NullInt64 | ||
| FreeSpace sql.NullInt64 | ||
| } | ||
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| func (e *tablespaceExtractor) tempFreeSpaceData(ctx context.Context) ([]tempFreeSpace, error) { | ||
| rows, err := e.db.QueryContext(ctx, `WITH sums AS ( SELECT (SELECT SUM(BYTES) FROM DBA_DATA_FILES) + (SELECT SUM(BYTES) FROM DBA_TEMP_FILES) AS TOTAL_SUM FROM dual ) SELECT t.TABLESPACE_NAME, s.TOTAL_SUM, t.ALLOCATED_SPACE, t.FREE_SPACE FROM DBA_TEMP_FREE_SPACE t, sums s `) | ||
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There was a problem hiding this comment. Can you consider something simple as below There was a problem hiding this comment. Talking about Niraj's query: See this. (You are using cross join with CTE and DBA_TEMP_FREE_SPACE). Now that I read more and more on this I keep on finding something new. In the query below, the scalar subquery is used to get the TOTAL_SUM from sums CTE compared to your query where CTE is cross-joined with DBA_TEMP_FREE_SPACE. From what I read in most places, scalar subquery seems to be generally a better choice in terms of perf and readability. For example, As the same scalar subquery is running for each row, Oracle might as well cache it and keep using it. In the case of cross joins, it takes up a lot of memory to create a temp table to do the join (unless the DB optimizes it). Find more here: See: https://stackoverflow.com/a/55192080/5821408 and https://asktom.oracle.com/Misc/oramag/on-caching-and-evangelizing-sql.html Try this query? This query will calculate the total sum separately and display it as a single value for each row. No cross joins. |
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| if err != nil { | ||
| return nil, fmt.Errorf("error executing query: %w", err) | ||
| } | ||
| defer rows.Close() | ||
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| results := make([]tempFreeSpace, 0) | ||
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| for rows.Next() { | ||
| dest := tempFreeSpace{} | ||
| if err = rows.Scan(&dest.TablespaceName, &dest.TotalSpaceBytes, &dest.UsedSpaceBytes, &dest.FreeSpace); err != nil { | ||
| return nil, err | ||
| } | ||
| results = append(results, dest) | ||
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