- A place to find some useful scripts (database related Unix shell / SQL / PL/SQL / monitoring / Tuning etc.) : Orafaq
- Oracle Apps (applications) / E-business suite related tips : Searchoracle
- A useful book available on Oracle Database Normalization . I'll review this soon & post here.
How many times have you thought of calculating HWM (high watermark) of a tablespace as a DBA ? Have you ever found out that a tablespace is overallocated in a database, as compared to the data being used in it ? In such a case, you'd want to reduce the wasted space & resize the tablespace to a smaller size, although greater than the current usage. HWM is at the maximum blocks ever occupied by a SEGMENT (unless we perform a truncate on it). Segments span over datafiles however remain within a tablespace. All segments are physically allocated by way of extents, which are contiguous blocks of data. Now, when we talk about contiguous blocks, 2 datafiles (even from same tablespace) are highly unlikely to have contiguguos data blocks. Hence, theoretically, it's possible to calculate high watermark within a datafile, not a tablespace directly, as the latter is only a logical unit. Although, we can resize a tablespace, however the resize value needs to be based on exact calculati...
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