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Archives of the TeradataForumMessage Posted: Thu, 25 May 2007 @ 00:12:38 GMT
Hi John, There are a few tables that you have a look at for stats dbc.tvfields dbc.ColumnStats dbc.Indexes dbc.IndexStats dbc.MultiColumnStats There is a field on each of these tables called fieldStatistics or IndexStatistics if Stats have been collect on the column/index. If you want to interrogate dbc.tvfields I got the code below a few years ago on this forum from Dieter Noeth which works on V2R5.1 (Fair play Dieter!) Fachtna O'Donovan This technique may be used to extract additional information from the binary statistics: - Row count - Number of distinct values - Number of NULLs - Modal Frequency, i.e. maximum number of rows / value /** Additional info on collected statistics, including Date, Time, Rowcount... 2003-03-12 dn initial version **/ SELECT DatabaseName, TableName, ColumnName, /** stats collected on: 'C' --> Column 'I' --> Index 'M' --> Multiple columns (V2R5) **/ StatsType, /** collect stats date **/ CollectDate, /** collect stats time **/ CollectTime, /** V2R5: sample size used for collect stats**/ CASE SampleSize WHEN 0 THEN 100 ELSE SampleSize END AS SampleSize, /** Row Count Estimated when SampleSize < 100 **/ (-1**(NumRowsw1 / 32768)) * (2**((NumRowsw1 / 16 mod 2048) - 1023)) * (1 + ((NumRowsw1 mod 16) * 2**-4) + (NumRowsw2 * 2**-20) + (NumRowsw3 * 2**-36) + (NumRowsw4 * 2**-52)) (decimal(18,0)) AS NumRows, /** Distinct Values Estimated when SampleSize < 100 **/ (-1**(NumValuesw1 / 32768)) * (2**((NumValuesw1 / 16 mod 2048) - 1023)) * (1 + ((NumValuesw1 mod 16) * 2**-4) + (NumValuesw2 * 2**-20) + (NumValuesw3 * 2**-36) + (NumValuesw4 * 2**-52)) (decimal(18,0)) AS NumValues, /** Number of NULLs Estimated when SampleSize < 100 **/ (-1**(NumNullsw1 / 32768)) * (2**((NumNullsw1 / 16 mod 2048) - 1023)) * (1 + ((NumNullsw1 mod 16) * 2**-4) + (NumNullsw2 * 2**-20) + (NumNullsw3 * 2**-36) + (NumNullsw4 * 2**-52)) (decimal(18,0)) AS NumNulls, /** Maximum number of rows / value, Estimated when SampleSize < 100 **/ (-1**(ModeFreqw1 / 32768)) * (2**((ModeFreqw1 / 16 mod 2048) - 1023)) * (1 + ((ModeFreqw1 mod 16) * 2**-4) + (ModeFreqw2 * 2**-20) + (ModeFreqw3 * 2**-36) + (ModeFreqw4 * 2**-52)) (decimal(18,0)) AS ModeFreq FROM ( SELECT DatabaseName, TableName, ColumnName, Stats, StatsType, ( (HASHBUCKET (SUBSTR(Stats, 2, 1) || SUBSTR(Stats, 1, 1) (BYTE(4)) ) - 1900 ) * 10000 + (HASHBUCKET ('00'xb || SUBSTR(Stats, 3, 1) (BYTE(4)) ) ) * 100 + (HASHBUCKET ( '00'xb || SUBSTR(Stats, 4, 1) (BYTE(4)) ) ) ) (DATE) AS CollectDate, (CAST( (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 5, 1) AS BYTE(4)) ) (FORMAT '99:') ) || (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 6, 1) AS BYTE(4)) ) (FORMAT '99:') ) || (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 7, 1) AS BYTE(4)) ) (FORMAT '99.') ) || (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 8, 1) AS BYTE(4)) ) (FORMAT '99') ) AS TIME(2)) ) AS CollectTime, HASHBUCKET ('00'xb || SUBSTR(Stats, 12, 1) (BYTE(4))) AS SampleSize, HASHBUCKET(SUBSTR(Stats, 12 + 8, 1) || SUBSTR(Stats, 12 + 7, 1) (BYTE(4))) AS NumNullsw1, HASHBUCKET(SUBSTR(Stats, 12 + 6, 1) || SUBSTR(Stats, 12 + 5, 1) (BYTE(4))) AS NumNullsw2, HASHBUCKET(SUBSTR(Stats, 12 + 4, 1) || SUBSTR(Stats, 12 + 3, 1) (BYTE(4))) AS NumNullsw3, HASHBUCKET(SUBSTR(Stats, 12 + 2, 1) || SUBSTR(Stats, 12 + 1, 1) (BYTE(4))) AS NumNullsw4, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 8, 1) || SUBSTR(Stats, 40 + Offset + 7, 1) (BYTE(4))) AS ModeFreqw1, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 6, 1) || SUBSTR(Stats, 40 + Offset + 5, 1) (BYTE(4))) AS ModeFreqw2, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 4, 1) || SUBSTR(Stats, 40 + Offset + 3, 1) (BYTE(4))) AS ModeFreqw3, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 2, 1) || SUBSTR(Stats, 40 + Offset + 1, 1) (BYTE(4))) AS ModeFreqw4, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 8, 1) || SUBSTR(Stats, 48 + Offset + 7, 1) (BYTE(4))) AS NumValuesw1, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 6, 1) || SUBSTR(Stats, 48 + Offset + 5, 1) (BYTE(4))) AS NumValuesw2, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 4, 1) || SUBSTR(Stats, 48 + Offset + 3, 1) (BYTE(4))) AS NumValuesw3, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 2, 1) || SUBSTR(Stats, 48 + Offset + 1, 1) (BYTE(4))) AS NumValuesw4, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 8, 1) || SUBSTR(Stats, 56 + Offset + 7, 1) (BYTE(4))) AS NumRowsw1, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 6, 1) || SUBSTR(Stats, 56 + Offset + 5, 1) (BYTE(4))) AS NumRowsw2, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 4, 1) || SUBSTR(Stats, 56 + Offset + 3, 1) (BYTE(4))) AS NumRowsw3, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 2, 1) || SUBSTR(Stats, 56 + Offset + 1, 1) (BYTE(4))) AS NumRowsw4 FROM ( SELECT d.databasename AS DatabaseName, t.tvmname AS TableName, /** Concat up to 16 columnnames into a comma delimited list **/ MAX(CASE WHEN i.FieldPosition = 1 THEN TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 2 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 3 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 4 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 5 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 6 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 7 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 8 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 9 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 10 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 11 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 12 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 13 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 14 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 15 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition = 16 THEN ',' || TRIM(c.FieldName) ELSE '' END) || MAX(CASE WHEN i.FieldPosition > 16 THEN ',...' ELSE '' END) AS ColumnName, CASE WHEN IndexType = 'M' THEN 'M' ELSE 'I' END AS StatsType, /** Floats are stored after the data and data may be 16 or 32 BYTEs **/ /** depending on BYTE[23]**/ MAX(CASE WHEN SUBSTR(i.indexStatistics, 23, 1) = '00'XB THEN 16 ELSE 0 END) AS Offset, MAX(SUBSTR(i.indexstatistics, 1, 80)) AS Stats FROM dbc.dbase d JOIN dbc.tvm t ON d.databaseid = t.databaseid JOIN dbc.tvfields c ON t.tvmid = c.tableid JOIN dbc.Indexes i ON c.tableid = i.tableid AND c.fieldid = i.fieldid GROUP BY DatabaseName, TableName, StatsType, i.IndexNumber UNION ALL SELECT d.databasename AS DatabaseName, t.tvmname AS TableName, c.fieldname AS ColumnName, 'C' AS StatsType, /** Floats are stored after the data and data may be 16 or 32 BYTEs **/ /** depending on BYTE[23]**/ CASE WHEN SUBSTR(c.fieldStatistics, 23, 1) = '00'XB THEN 16 ELSE 0 END AS Offset, SUBSTR(c.fieldstatistics, 1, 80) AS Stats FROM dbc.dbase d JOIN dbc.tvm t ON d.databaseid = t.databaseid JOIN dbc.tvfields c ON t.tvmid = c.tableid ) dt ) dt WHERE Stats IS NOT NULL ORDER BY DatabaseName, TableName, ColumnName ; /*** Modified view dbc.ColumnStats. dbc.IndexStats and dbc.MultiColumnStats may be modified in a similar way ***/ SELECT DatabaseName, TableName, ColumnName, ColumnType, ColumnLength, ColumnFormat, DecimalTotalDigits, DecimalFractionalDigits, Stats AS FieldStatistics, SeqNumber, /** collect stats date **/ CollectDate, /** collect stats time **/ CollectTime, /** V2R5: sample size used for collect stats**/ CASE SampleSize WHEN 0 THEN 100 ELSE SampleSize END AS SampleSize, /** Row Count Estimated when SampleSize < 100 **/ (-1**(NumRowsw1 / 32768)) * (2**((NumRowsw1 / 16 mod 2048) - 1023)) * (1 + ((NumRowsw1 mod 16) * 2**-4) + (NumRowsw2 * 2**-20) + (NumRowsw3 * 2**-36) + (NumRowsw4 * 2**-52)) (decimal(18,0)) AS NumRows, /** Distinct Values Estimated when SampleSize < 100 **/ (-1**(NumValuesw1 / 32768)) * (2**((NumValuesw1 / 16 mod 2048) - 1023)) * (1 + ((NumValuesw1 mod 16) * 2**-4) + (NumValuesw2 * 2**-20) + (NumValuesw3 * 2**-36) + (NumValuesw4 * 2**-52)) (decimal(18,0)) AS NumValues, /** Number of NULLs Estimated when SampleSize < 100 **/ (-1**(NumNullsw1 / 32768)) * (2**((NumNullsw1 / 16 mod 2048) - 1023)) * (1 + ((NumNullsw1 mod 16) * 2**-4) + (NumNullsw2 * 2**-20) + (NumNullsw3 * 2**-36) + (NumNullsw4 * 2**-52)) (decimal(18,0)) AS NumNulls, /** Maximum number of rows / value, Estimated when SampleSize < 100 **/ (-1**(ModeFreqw1 / 32768)) * (2**((ModeFreqw1 / 16 mod 2048) - 1023)) * (1 + ((ModeFreqw1 mod 16) * 2**-4) + (ModeFreqw2 * 2**-20) + (ModeFreqw3 * 2**-36) + (ModeFreqw4 * 2**-52)) (decimal(18,0)) AS ModeFreq FROM ( SELECT DatabaseName, TableName, ColumnName, ColumnType, ColumnLength, ColumnFormat, DecimalTotalDigits, DecimalFractionalDigits, Stats, SeqNumber, ( (HASHBUCKET (SUBSTR(Stats, 2, 1) || SUBSTR(Stats, 1, 1) (BYTE(4)) ) - 1900 ) * 10000 + (HASHBUCKET ('00'xb || SUBSTR(Stats, 3, 1) (BYTE(4)) ) ) * 100 + (HASHBUCKET ( '00'xb || SUBSTR(Stats, 4, 1) (BYTE(4)) ) ) ) (DATE) AS CollectDate, (CAST( (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 5, 1) AS BYTE(4)) ) (FORMAT '99:') ) || (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 6, 1) AS BYTE(4)) ) (FORMAT '99:') ) || (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 7, 1) AS BYTE(4)) ) (FORMAT '99.') ) || (HASHBUCKET (CAST('00'xb || SUBSTR(Stats, 8, 1) AS BYTE(4)) ) (FORMAT '99') ) AS TIME(2)) ) AS CollectTime, HASHBUCKET ('00'xb || SUBSTR(Stats, 12, 1) (BYTE(4))) AS SampleSize, HASHBUCKET(SUBSTR(Stats, 12 + 8, 1) || SUBSTR(Stats, 12 + 7, 1) (BYTE(4))) AS NumNullsw1, HASHBUCKET(SUBSTR(Stats, 12 + 6, 1) || SUBSTR(Stats, 12 + 5, 1) (BYTE(4))) AS NumNullsw2, HASHBUCKET(SUBSTR(Stats, 12 + 4, 1) || SUBSTR(Stats, 12 + 3, 1) (BYTE(4))) AS NumNullsw3, HASHBUCKET(SUBSTR(Stats, 12 + 2, 1) || SUBSTR(Stats, 12 + 1, 1) (BYTE(4))) AS NumNullsw4, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 8, 1) || SUBSTR(Stats, 40 + Offset + 7, 1) (BYTE(4))) AS ModeFreqw1, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 6, 1) || SUBSTR(Stats, 40 + Offset + 5, 1) (BYTE(4))) AS ModeFreqw2, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 4, 1) || SUBSTR(Stats, 40 + Offset + 3, 1) (BYTE(4))) AS ModeFreqw3, HASHBUCKET(SUBSTR(Stats, 40 + Offset + 2, 1) || SUBSTR(Stats, 40 + Offset + 1, 1) (BYTE(4))) AS ModeFreqw4, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 8, 1) || SUBSTR(Stats, 48 + Offset + 7, 1) (BYTE(4))) AS NumValuesw1, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 6, 1) || SUBSTR(Stats, 48 + Offset + 5, 1) (BYTE(4))) AS NumValuesw2, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 4, 1) || SUBSTR(Stats, 48 + Offset + 3, 1) (BYTE(4))) AS NumValuesw3, HASHBUCKET(SUBSTR(Stats, 48 + Offset + 2, 1) || SUBSTR(Stats, 48 + Offset + 1, 1) (BYTE(4))) AS NumValuesw4, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 8, 1) || SUBSTR(Stats, 56 + Offset + 7, 1) (BYTE(4))) AS NumRowsw1, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 6, 1) || SUBSTR(Stats, 56 + Offset + 5, 1) (BYTE(4))) AS NumRowsw2, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 4, 1) || SUBSTR(Stats, 56 + Offset + 3, 1) (BYTE(4))) AS NumRowsw3, HASHBUCKET(SUBSTR(Stats, 56 + Offset + 2, 1) || SUBSTR(Stats, 56 + Offset + 1, 1) (BYTE(4))) AS NumRowsw4 FROM ( SELECT d.databasename AS DatabaseName, t.tvmname AS TableName, c.fieldname AS ColumnName, c.FieldType AS ColumnType, c.MaxLength AS ColumnLength, c.FieldFormat AS ColumnFormat, c.TotalDigits AS DecimalTotalDigits, c.ImpliedPoint AS DecimalFractionalDigits, c.FieldStatistics AS Stats, c.FieldID AS SeqNumber, /** Floats are stored after the data and data may be 16 or 32 BYTEs **/ /** depending on BYTE[23]**/ CASE WHEN SUBSTR(c.fieldStatistics, 23, 1) = '00'XB THEN 16 ELSE 0 END AS Offset FROM dbc.dbase d JOIN dbc.tvm t ON d.databaseid = t.databaseid JOIN dbc.tvfields c ON t.tvmid = c.tableid ) dt ) dt;
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