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HP NonStop Shadowbase Command Definitions

Database Specification Command Descriptions

HP NonStop Shadowbase Command Reference Manual—785421-002

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UPDATEs to all other records in the source (i.e., updates to any

other record than the first record in the file) are applied to the target

using the alternate key specifier provided in DBS parameter

KEYSPECIFIER. The alternate key indicated by KEYSPECIFIER

does not have to be unique. The UPDATE will only be applied to

the first occurrence of an alternate key match along the specified

path.

Source delete events are ignored and logged if the

BASE24_MSG_LEVEL > 0.

Updates with a record length different from the target record will be

logged and ignored (you cannot update an entry-sequenced file

with a different record length).

If the DBS BEFOREVALUES is ON, the the source’s “before” value

of the alternate key fields is used for positioning. Hence,

BEFOREVALUES should normally be enabled. However, setting

the BEFOREVALUES to ON increases the data replication traffic as

now both the before and the after values are replicated for an

UPDATE (otherwise, only the after values are replicated). You can

turn BEFOREVALUES to OFF (the default) if you are sure that your

application does not change the PR alternate key file field values.

When BEFOREVALUES is set to OFF, HP Shadowbase uses the

source’s after image key values for positioning.

In other words if the alternate key value is likely to change,

then BEFOREVALUES of the DBS should be set to ON,

otherwise target database corruption will result as HP

Shadowbase will potentially update the wrong target record.

<Bit4> Entry Sequenced file replication and BASE24 handling of DML

events (e.g., a BASE24 ILF file) with variable length records. When

enabled, the header records (relative record 0) are always

replicated to the appropriate target location’s header record

(INSERT and UPDATEs to the source’s header record are always

applied to the header record of the target file, either as an insert or

an update/overlay of what is at that position).

UPDATEs to all other records in the source (i.e.,i.e., updates to any

other record than the first record in the file) are applied to the target

using the “PR” alternate key specifier for positioning. The “PR” key

specifier must exist for these files but does not have to be unique

(HP Shadowbase uses the “PR” alternate key definition to get the

alternate key’s offset and length). If the alternate key of the target

file contains multiple records for the same alternate key value, the

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