Read a row - Tablestore SDK for Go - Tablestore - Alibaba Cloud Documentation Center

Prerequisites

Install the Tablestore SDK for Go and initialize the client.

Description

Call GetRow to read a row by specifying its complete primary key. You can limit the returned attribute columns, data versions, and version time range, or use a filter to screen attribute columns.

func (tableStoreClient *TableStoreClient) GetRow(request *GetRowRequest) (*GetRowResponse, error)

The following sample reads the row whose primary key value is row1 from the example_table table.

primaryKey := &tablestore.PrimaryKey{}
primaryKey.AddPrimaryKeyColumn("id", "row1")

request := &tablestore.GetRowRequest{
    SingleRowQueryCriteria: &tablestore.SingleRowQueryCriteria{
        TableName:  "example_table",
        PrimaryKey: primaryKey,
        MaxVersion: 1,
    },
}

response, err := client.GetRow(request)
if err != nil {
    log.Fatal(err)
}

fmt.Println(response.PrimaryKey)
fmt.Println(response.Columns)

Parameters

GetRowRequest contains the following parameter.

Name	Type	Description
SingleRowQueryCriteria (required)	`*SingleRowQueryCriteria`	The row query criteria.

Row query criteria

SingleRowQueryCriteria contains the following parameters.

Name	Type	Description
TableName (required)	`string`	The table name.
PrimaryKey (required)	`*PrimaryKey`	The complete primary key of the row. To read a row that contains an auto-increment primary key column, also specify the actual auto-increment value.
MaxVersion (optional)	`int32`	The maximum number of versions to return. At least one of `MaxVersion` and `TimeRange` is required.
TimeRange (optional)	`*TimeRange`	The version time range, which specifies a start time, end time, or exact version in milliseconds. At least one of `MaxVersion` and `TimeRange` is required.
ColumnsToGet (optional)	`[]string`	The attribute columns to return. If this parameter is not specified, all attribute columns are returned. If both `ColumnsToGet` and `Filter` are specified, Tablestore first selects the columns specified by `ColumnsToGet` and then applies `Filter` to the selected columns. If `Filter` references a column that is not included in `ColumnsToGet`, the column is treated as missing. Whether the row is filtered out is determined by `FilterIfMissing`.
Filter (optional)	`ColumnFilter`	The attribute column filter. For more information, see Use filters.
StartColumn (optional)	`*string`	The start attribute column of the name range. This column is included in the result.
EndColumn (optional)	`*string`	The end attribute column of the name range. This column is excluded from the result.
TransactionId (optional)	`*string`	The local transaction ID. Specify this parameter only for a read in a local transaction. For more information, see Use local transactions.

Response

GetRowResponse contains the following business information. If the row does not exist, the response does not contain a primary key or attribute columns.

Field	Type	Description
`PrimaryKey`	`PrimaryKey`	The primary key of the row.
`Columns`	`[]*AttributeColumn`	The returned attribute columns, values, and versions.

Examples

Read data versions in a time range

The following sample reads data versions generated within the previous day.

now := time.Now().UnixMilli()
request.SingleRowQueryCriteria.MaxVersion = 0
request.SingleRowQueryCriteria.TimeRange = &tablestore.TimeRange{
    Start: now - 24*60*60*1000,
    End:   now,
}