Count documents (Go)
Counts documents in a collection using filter clauses.
Exact counting of the number of documents is a slow, expensive operation. If the document count exceeds the upper limit set by you or by the API, an indication of this limit will be returned instead of the full count.
If you need to count large numbers of documents, consider using the method to estimate count or the DataStax Bulk Loader instead.
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Ready to write code? See the examples for this method to get started. If you are new to the Data API, check out the quickstart. |
Result
Returns an integer indicating the exact number of documents that match the specified filter.
If the count exceeds the caller-provided or API-set upper bound, the client returns ErrTooManyDocumentsToCount.
Parameters
Use the CountDocuments method, which belongs to the Collection type.
Method signature
func (c *Collection) CountDocuments(
ctx context.Context,
f CollectionFilter,
upperBound int,
opts ...options.CollectionCountDocumentsOption
) (int, error)| Name | Type | Summary |
|---|---|---|
|
|
The context for the operation. |
|
An object that defines filter criteria using the Data API filter syntax. The method only finds documents that match the filter criteria. Filters can improve performance by reducing the number of documents that the Data API processes. You must use For a list of available filter operators and more examples, see Filter operators for collections (Go). Filters can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in a filter. For an example, see Count documents that match a filter. |
|
|
|
The maximum number of documents to count. If the actual number of documents exceeds this value or exceeds the limit set by the Data API, the client will return an error. |
|
Optional.
A builder to generate options for this operation.
See Methods of the |
| Method | Summary |
|---|---|
|
Optional. General API options for this operation, including the timeout. |
Examples
The following examples demonstrate how to count documents in a collection.
Count documents that match a filter
You can use a filter to count documents that match specific criteria.
For a list of available filter operators and more examples, see Filter operators for collections (Go).
Filters can use only indexed fields. If you apply selective indexing when you create a collection, you cannot reference non-indexed fields in a filter.
package main
import (
"context"
"fmt"
"log"
"github.com/datastax/astra-db-go/v2/astra"
"github.com/datastax/astra-db-go/v2/astra/filter"
"github.com/datastax/astra-db-go/v2/astra/options"
)
func main() {
ctx := context.Background()
// Get an existing collection
client := astra.NewClient(
options.API().SetEnvironment(options.EnvironmentHCD),
)
database := client.Database(
"API_ENDPOINT",
options.API().
SetUsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD",
).
SetKeyspace("KEYSPACE_NAME"),
)
collection := database.Collection("COLLECTION_NAME")
// Count documents
count, err := collection.CountDocuments(
ctx,
filter.And(
filter.Eq("is_checked_out", false),
filter.Lt("number_of_pages", 300),
),
500,
)
if err != nil {
log.Fatal(err)
}
fmt.Println(count)
}Count all documents
To attempt to count all documents, use an empty filter.
package main
import (
"context"
"fmt"
"log"
"github.com/datastax/astra-db-go/v2/astra"
"github.com/datastax/astra-db-go/v2/astra/options"
)
func main() {
ctx := context.Background()
// Get an existing collection
client := astra.NewClient(
options.API().SetEnvironment(options.EnvironmentHCD),
)
database := client.Database(
"API_ENDPOINT",
options.API().
SetUsernamePasswordTokenProvider(
"USERNAME",
"PASSWORD",
).
SetKeyspace("KEYSPACE_NAME"),
)
collection := database.Collection("COLLECTION_NAME")
// Count documents
count, err := collection.CountDocuments(ctx, nil, 500)
if err != nil {
log.Fatal(err)
}
fmt.Println(count)
}Client reference
For more information, see the client reference.
