Writer Mode

Many writers that do not support theFeature Operationspecification share a Writer Mode specification,which determines whether incoming features will be inserted,updated,or deleted from the destination tables.Some writers deviate from the specification.

The writer mode can be specified at three unique levels:

• Writer
• Table
• Feature

Writer Level

At the writer level,the keyword is _MODE ,prefixed by the writer keyword (for example,SDE30).Possible values are:

• INSERT – Implies insert only;can be overridden only by table-level modes,not feature-level modes.
• UPDATE – Update table,but can be overridden by table- and feature-level modes.
• DELETE – Delete from table,but can be overridden by table- and feature-level modes.

Table Level

At the table level,there is a format specific feature type DEF line parameter called _MODE prefixed by the writer keyword (for example,SDE30_MODE).Possible values for this attribute are:

0.INHERIT_FROM_WRITER – Inherits the writer-level writer mode.

1.INSERT

2.UPDATE

3.DELETE

Feature Level

At the feature level,the writer mode can be set by an attribute named fme_db_operation.Possible values for this attribute are:

0. – Defaults to table level mode
1.INSERT
2.UPDATE
3.DELETE

fme_db_operation overrides the writer and table level writer modes,except for when the table level mode is INSERT,or if the table level mode is INHERIT_FROM_WRITER and writer level mode is INSERT.

fme_db_operation is used in conjunction with update/delete key columns,or with the fme_where attribute for update and delete operations at the feature level.If a writer supports both fme_where and update/delete key columns,fme_where overrides update/delete key columns.

Insert example:

WRITER LEVEL: UPDATE
TABLE LEVEL: UPDATE,INSERT or DELETE
feature type roads
num_lanes 5
surface_type gravel
age 106
location canada
condition poor
name Highway 1
road_id 1234
fme_geometry fme_no_geom
fme_db_operation INSERT

This will insert a row into a table named "roads".This will append to an existing table.Columns not specified will receive their default values,if there are default values.

Update example:

WRITER LEVEL: UPDATE
TABLE LEVEL: UPDATE or DELETE
feature type roads
condition good
fme_db_operation UPDATE
fme_where road_id = 1234

This will update the row in the table "roads" where the road_id = 1234.The column "condition" will have its value changed from "poor" to "good".

Delete example:

WRITER LEVEL: UPDATE
TABLE LEVEL: UPDATE or DELETE
feature type roads
fme_db_operation DELETE
fme_where road_id = 1234

This will delete the row in the table "roads" where the road_id = 1234.

Notes:

• Updates performed on rows that DO NOT EXIST are NOT turned into inserts.The user is warned and the feature is rejected.
• Inserts performed on rows that EXIST are NOT turned into updates.FME will still attempt to perform the insert: if it is not prevented by a unique index,it will insert a duplicate row;if it is prevented by a unique index,the feature will be rejected,or translation will fail,depending on the writer.
• Updates are not limited to one row per feature.It is possible to update the entire table with one feature.

• Geometry can also be updated using update mode.The geometry on the update feature will replace the geometry in all of the matched rows,with one exception.If a feature has no geometry,the destination geometry column will either be replaced with a null value,or not be updated,depending on the writer.