Options for creating a new transaction.
| JSON representation | 
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{ // Union field  | 
            
| Fields | |
|---|---|
Union field mode. The mode of the transaction. mode can be only one of the following: | 
            |
readOnly | 
              
                 
 The transaction can only be used for read operations.  | 
            
readWrite | 
              
                 
 The transaction can be used for both read and write operations.  | 
            
ReadOnly
Options for a transaction that can only be used to read documents.
| JSON representation | 
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{ // Union field  | 
              
| Fields | |
|---|---|
Union field consistency_selector. The consistency mode for this transaction. If not set, defaults to strong consistency. consistency_selector can be only one of the following: | 
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readTime | 
                
                   
 Reads documents at the given time. This must be a microsecond precision timestamp within the past one hour, or if Point-in-Time Recovery is enabled, can additionally be a whole minute timestamp within the past 7 days. Uses RFC 3339, where generated output will always be Z-normalized and use 0, 3, 6 or 9 fractional digits. Offsets other than "Z" are also accepted. Examples:   | 
              
ReadWrite
Options for a transaction that can be used to read and write documents.
Firestore does not allow 3rd party auth requests to create read-write. transactions.
| JSON representation | 
|---|
{ "retryTransaction": string }  | 
              
| Fields | |
|---|---|
retryTransaction | 
                
                   
 An optional transaction to retry. A base64-encoded string.  |