docs: default values (#986)

* changes

* Changes

* changes

docs/data-types/mysql.md

@@ -139,8 +139,12 @@ and `ON UPDATE` actions, we drop them.
 
 ## Default Values
 
-While Spanner supports default values, Spanner migration tool currently does not support translating source `DEFAULT` constraints to Spanner `DEFAULT` constraints. We drop the `DEFAULT` MySQL constraint during conversion.
-It can be manually added to the DDL via an `ALTER TABLE` command.
+The Spanner Migration Tool automatically migrates all `DEFAULT` values from a MySQL source
+to a GoogleSQL destination, provided they can be mapped without modification.
+Any `DEFAULT` constraints that cannot be mapped are dropped, and a warning is issued. 
+Users can edit the column to change the `DEFAULT` constraints. The validity of the `DEFAULT`
+constraints will be verified when users try to move to the Prepare Migration page. In case
+of any errors users will not be able to proceed until all `DEFAULT` constraints are valid.
 
 ## Check Constraints
 

docs/data-types/postgres.md

@@ -141,8 +141,12 @@ Spanner doesn't support `ON DELETE` and `ON UPDATE` actions, so we drop these.
 
 ## Default Values
 
-While Spanner supports default values, Spanner migration tool currently does not support translating source `DEFAULT` constraints to Spanner `DEFAULT` constraints. We drop the `DEFAULT` MySQL constraint during conversion.
-It can be manually added to the DDL via an `ALTER TABLE` command.
+The Spanner Migration Tool automatically migrates all `DEFAULT` values from a MySQL source
+to a PostgreSQL destination, provided they can be mapped without modification.
+Any `DEFAULT` constraints that cannot be mapped are dropped, and a warning is issued. 
+Users can edit the column to change the `DEFAULT` constraints. The validity of the `DEFAULT`
+constraints will be verified when users try to move to the Prepare Migration page. In case
+of any errors users will not be able to proceed until all `DEFAULT` constraints are valid.
 
 ## Secondary Indexes
 

docs/ui/schema-conv/issues.md

@@ -28,10 +28,12 @@ Spanner migration tool scans through the generated spanner schema and notifies t
 - Addition of [synthetic primary key](../ui.md/#termsterminology) - synth_id
 - [Hotspotting](https://cloud.google.com/spanner/docs/schema-design) due to timestamp or auto-increment keys
 - Auto Increment has been converted to Sequence, set Ignore Range or Start with Counter to avoid duplicate value errors
+- Dropping unsupported default values during schema migration.
 
 ## Errors
 
 - Detection of unsupported check constraints in spanner.
+- Detection of invalid default values in spanner added during column modification.
 - Data type mismatch of referenced column in check constraints.
 - Referenced column in check constraints not found.
 - Function referenced in check constraints is not found. 

docs/ui/schema-conv/spanner-draft.md

@@ -26,17 +26,17 @@ Users can view detailed information for a table by selecting it from the **Spann
 
 ### Column
 
-Column tab provides information on the columns that are a part of the selected table. It also provides the option to edit the column wherein a user can modify a column name, delete a column, change the data type of the column, add auto-generation to the column or modify the null property of the column. Once the user is done with required modifications, they can click on **SAVE & CONVERT **and the update would reflect in the session file and across all the components in the database.
+Column tab provides information on the columns that are a part of the selected table. It also provides the option to edit the column wherein a user can modify a column name, delete a column, change the data type of the column, add auto-generation to the column, modify the default value or modify the null property of the column. Once the user is done with required modifications, they can click on **SAVE & CONVERT **and the update would reflect in the session file and across all the components in the database.
 
-![](https://services.google.com/fh/files/misc/column-info-edit.png)
+![](https://services.google.com/fh/files/misc/dv1.png)
 
 #### Add Column
 
 In addition to editing the existing columns in the Spanner draft mapped from the source database, users can also add new columns to the selected table.
 
-![](https://services.google.com/fh/files/misc/add_column.png)
+![](https://services.google.com/fh/files/misc/dv4.png)
 ![](https://services.google.com/fh/files/misc/add_column_form.png)
-![](https://services.google.com/fh/files/misc/new_column.png)
+![](https://services.google.com/fh/files/misc/dvv3.png)
 
 To specify custom transformation logic in the dataflow pipeline to populate these columns, please refer to the [Custom Transformation](../../transformations/CustomTransformation.md) section.