How should I decide on the max size of the CLOB fields in the tables Batch_Job_Execution_Context and Batch_Step_Execution_Context. Do we need to set this as 4GB always. How do we estimate the max size of this for my project? What is the recommended practice?
Related
I somehow want to calculate partition overhead for very small tables. I have a Oracle DB with 5K tables sizing from lets say 10KB to 1TB. All of them are range partitioned based on a DATE column. What I want to calculate is the difference in the table size if I will store all data in 1 partition Vs if I store it in lets say 30 partitions. Block Size is 16KB.
I'm newbie on Oracle and I want to know the following limitations on Oracle 12 :
Maximum Database Size
Maximum Table Size
Maximum Row Size
Maximum Rows per Table
Maximum Columns per Table
Maximum Indexes per Table
Currently I found these limitations
Maximum Database Size = 8000T
Maximum Table Size
Maximum Row Size
Maximum Rows per Table = Unlimited
Maximum Columns per Table = 1000
Maximum Indexes per Table = Unlimited
Thank you for your help
All this information is in the docs:
Physical limits:
https://docs.oracle.com/database/121/REFRN/GUID-939CB455-783E-458A-A2E8-81172B990FE9.htm
Logical limits:
https://docs.oracle.com/database/122/REFRN/logical-database-limits.htm
Maximum row size:
For Oracle8, Release 8.0 and later, the answer is 4,000GB (or 4GB per
LOB, 1,000 LOBs per table). Just take the maximum varchar2 size (4000)
or char size (2000) and add them up—4000x1000=4,000,000 bytes of
structured data.
I am partitioning a table in Oracle 11g using a list partition. The list partition is based upon an arbitrary id which we are grouping.
For instance:
PARTITION BY LIST (id)
( PARTITION 1 VALUES (2345,7433,3857,2457,5757,3204) TABLESPACE T1
What is the maximum values that the partition values can take. Ie can 2345,7433,3857,2457,5757,3204 be extended infinitely or what is the max?
From the documentation:
The string comprising the list of values for each partition can be up to 4K bytes. The total number of values for all partitions cannot exceed 64K-1.
So there is no specific limit on the number of values in a single partition, as long as they fit into the 4K restriction - which you'd obviously hit before the overall 64K-1 limit.
(If you're grouping the IDs arbitrarily - which isn't quite what you said - then hash partitioning might be simpler that maintaining the value lists. Depends what you're actually doing though, and why.)
I am adding a column with datatype varchar2(1000), This column will be used to store a large set of message(approximately (600 characters).Does it effect the performance of query for having large datatype length, if so how? I will be having a query selecting that column occasionally. Does a table consume extra memory here even if the value in that field in some places 100 characters?
Does it affect performance? It depends.
If "adding a column" implies that you have an existing table with existing data that you're adding a new column to, are you going to populate the new column for old data? If so, depending on your PCTFREE settings and the existing size of the rows, increasing the size of every row by an average of 600 bytes could well lead to row migration which could potentially increase the amount of I/O that queries need to perform to fetch a row. You may want to create a new table with the new column and move the old data to the new table while simultaneously populating the new column if this is a concern.
If you have queries that involve full table scans on the table, anything that you do that increases the size of the table will negatively impact the speed of those queries since they now have to read more data.
When you increase the size of a row, you decrease the number of rows per block. That would tend to increase the pressure on your buffer cache so you'd either be caching fewer rows from this table or you'd be aging out some other blocks faster. Either of those could lead to individual queries doing more physical I/O rather than logical I/O and thus running longer.
A VARCHAR2(1000) will only use whatever space is actually required to store a particular value. If some rows only need 100 bytes, Oracle would only allocate 100 bytes within the block. If other rows need 900 bytes, Oracle would allocate 900 bytes within the block.
Is there some limit on the maximum total amount of data that can be stored in a single table in Oracle?
I think there shouldn't be because tables are anyways stored as a set of rows and rows can be chained as well. Does such a limit exist?
See Physical Database Limits and Logical Database Limits documentation.