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							88 lines
						
					
					
						
							2.5 KiB
						
					
					
				
			
		
		
	
	
							88 lines
						
					
					
						
							2.5 KiB
						
					
					
				'use strict';
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const MONGODB_ERROR_CODES = require('../error_codes').MONGODB_ERROR_CODES;
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const Aspect = require('./operation').Aspect;
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const defineAspects = require('./operation').defineAspects;
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const CommandOperationV2 = require('./command_v2');
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const maxWireVersion = require('../core/utils').maxWireVersion;
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const CountDocumentsOperation = require('./count_documents');
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class EstimatedDocumentCountOperation extends CommandOperationV2 {
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  constructor(collection, options) {
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    super(collection, options);
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    this.collection = collection;
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    this.collectionName = collection.s.namespace.collection;
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  }
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  execute(server, callback) {
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    if (maxWireVersion(server) < 12) {
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      return this.executeLegacy(server, callback);
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    }
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    // if the user specifies a filter, use a CountDocumentsOperation instead
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    if (this.options.query) {
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      const op = new CountDocumentsOperation(this.collection, this.options.query, this.options);
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      return op.execute(server, callback);
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    }
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    const pipeline = [{ $collStats: { count: {} } }, { $group: { _id: 1, n: { $sum: '$count' } } }];
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    const cmd = { aggregate: this.collectionName, pipeline, cursor: {} };
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    if (typeof this.options.maxTimeMS === 'number') {
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      cmd.maxTimeMS = this.options.maxTimeMS;
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    }
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    super.executeCommand(server, cmd, (err, response) => {
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      if (err && err.code !== MONGODB_ERROR_CODES.NamespaceNotFound) {
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        callback(err);
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        return;
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      }
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      callback(
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        undefined,
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        (response &&
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          response.cursor &&
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          response.cursor.firstBatch &&
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          response.cursor.firstBatch[0].n) ||
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          0
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      );
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    });
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  }
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  executeLegacy(server, callback) {
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    const cmd = { count: this.collectionName };
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    const options = this.options;
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    if (options.query) {
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      cmd.query = options.query;
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    }
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    if (options.hint) {
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      cmd.hint = options.hint;
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    }
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    if (typeof options.maxTimeMS === 'number') {
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      cmd.maxTimeMS = options.maxTimeMS;
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    }
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    if (typeof options.skip === 'number') {
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      cmd.skip = options.skip;
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    }
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    if (typeof options.limit === 'number') {
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      cmd.limit = options.limit;
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    }
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    super.executeCommand(server, cmd, (err, response) => {
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      if (err) {
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        callback(err);
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        return;
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      }
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      callback(null, response.n);
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    });
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  }
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}
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defineAspects(EstimatedDocumentCountOperation, [
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  Aspect.READ_OPERATION,
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  Aspect.RETRYABLE,
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  Aspect.EXECUTE_WITH_SELECTION
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]);
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module.exports = EstimatedDocumentCountOperation;
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