What is -DbCheck -AreaCheck -TableCheck and -IndexCheck?

Optional database startup parameters were added to enable physical consistency checks on record and index blocks in OpenEdge 10.1B02.  These checks are performed on index or record write operations only.  

The checks are offered at different levels to allow flexibility:

• Database level: "-DbCheck"

• DBDOWN when reported PHYSICAL index block corruption is reported.   
•  
• Area level: "-AreaCheck <area name>"

• Index level: "-IndexCheck <index name>"

• Table level: "-TableCheck <table name>"

The following precedence rules apply when enabling multiple parameters at the same time:

1. Each option can only be enabled once. For example, the following parameters are invalid:  -AreaCheck "Customer Area" -AreaCheck "Order Area"
2. If "-DbCheck" option is used with any other options, "-DbCheck" will have precedence and the consistency check will be applied on the whole database.
3. "-AreaCheck <area name>", "-IndexCheck <index name>" and "-TableCheck <table name>" can be used at the same time. The consistency check will be enabled for the superset of these options.  

Syntax for using runtime and roll forward physical checking:

    On the database primary login broker:
          _mprosrv <dbname> -S 5768 -B 100000 -L 100000 -DbCheck
    For a single user session:
          _progres <dbname> -p info.p -DbCheck
          _progres <dbname> -p info.p -AreaCheck "CustomerData"

    When using proutil:
         proutil <dbname> -DbCheck

    During roll forward:
          _rfutil dbname   -C roll forward -a /vfs/work/dbname.a1 -IndexCheck "Customer.name"
          _rfutil dbname   -C roll forward -a /vfs/work/dbname.a1 -TableCheck "Pub.Customer"

Physical consistency checks -DbCheck; -AreaCheck; -TableCheck and -IndexCheck may also be enabled online via the PROMON Administrative Functions Menu:
                
          OpenEdge Release Monitor (R&D)
          Enable/Disable block consistency check
   
           This option is used to enable/disable block consistency check.
    
           Current consistency check status:
    
                    1. -MemCheck:      disabled
                    2. -DbCheck:       disabled
                    3. -AreaCheck:     disabled
                    4. -IndexCheck:    disabled
                    5. -TableCheck:    disabled
    
          Enter the option to enable/disable a consistency check:
    
When should physical consistency checking be enabled?

These parameters (-DbCheck, -TableCheck, -IndexCheck) should only be used when there is some expectation of a problem in the database.  Examples of places where these parameters may be useful (but are not limited to) performing crash recovery or roll forward upon the database.  Errors detected when running with these parameters will be written to the database log file.

When errors are found they will not necessarily bring the database down unless a corruption is really found, but if a corruption is found, database integrity is preserved by forcing an Emergency shutdown.  The advantage of the physical checking is that corruption are likely to be found at the time as opposed to later when next accessed. When corruption are detected, the current operation will be halted and the routine will produce messages detailing the nature of the corruption to the lg file of the database.  In part these are 'proactive' utilities to help diagnose If there is a potential of overwriting memory or corrupt block. In effect, decrease the time needed to find (and fix) corruption when a crash issue results (usual utilites: dbrpr scans, idxfix, idxbuild dbtool etc) 

Example:

Usr 5: Invalid Record Block Detected
Usr 5: 15: D RL_RMCHG (PL) adbkey: 6/21504 updctr: 8 difLen: -1 flags:  recnum: 0 logOp: 1 recsz: 179 newsz: 200

Usr 6: Invalid Index Block Detected
Usr 6: 268: D RL_CXINS (PL) adbkey: 6/20768 updctr: 35 objDbkey: 64 root: 20768 offset: 3 cs: 0 extracs: 4 attr: 1 

Performance Impact of enabling physical consistency checks:

Enabling -DbCheck will result in a performance loss around 5% impacting operations requiring writes to the database. 
Performance losses from specific -AreaCheck, -TableCheck and -IdxCheck are smaller than -DbCheck (which is database wide)
 

Progress Articles: 

What is the -MemCheck Parameter?   
DBDOWN when reported PHYSICAL index block corruption is reported.