TableRowCountAction.java

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// to you under the Apache License, Version 2.0 (the
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//
//   http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.doris.httpv2.rest;

import org.apache.doris.catalog.Database;
import org.apache.doris.catalog.Env;
import org.apache.doris.catalog.OlapTable;
import org.apache.doris.catalog.Table;
import org.apache.doris.common.DorisHttpException;
import org.apache.doris.common.MetaNotFoundException;
import org.apache.doris.httpv2.entity.ResponseEntityBuilder;
import org.apache.doris.mysql.privilege.PrivPredicate;
import org.apache.doris.qe.ConnectContext;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * This class is responsible for fetch the approximate row count of the specified table from cluster-meta data,
 * the approximate row maybe used for some computing system to decide use which compute-algorithm can be used
 * such as shuffle join or broadcast join.
 * <p>
 * This API is not intended to compute the exact row count of the specified table, if you need the exact row count,
 * please consider using the sql syntax `select count(*) from {table}`
 */
@RestController
public class TableRowCountAction extends RestBaseController {

    @RequestMapping(path = "/api/{" + DB_KEY + "}/{" + TABLE_KEY + "}/_count", method = RequestMethod.GET)
    public Object count(
            @PathVariable(value = DB_KEY) final String dbName,
            @PathVariable(value = TABLE_KEY) final String tblName,
            HttpServletRequest request, HttpServletResponse response) {
        executeCheckPassword(request, response);
        // just allocate 2 slot for top holder map
        Map<String, Object> resultMap = new HashMap<>(4);
        try {
            String fullDbName = getFullDbName(dbName);
            // check privilege for select, otherwise return HTTP 401
            checkTblAuth(ConnectContext.get().getCurrentUserIdentity(), fullDbName, tblName, PrivPredicate.SELECT);
            OlapTable olapTable;
            try {
                Database db = Env.getCurrentInternalCatalog().getDbOrMetaException(fullDbName);
                olapTable = (OlapTable) db.getTableOrMetaException(tblName, Table.TableType.OLAP);
            } catch (MetaNotFoundException e) {
                return ResponseEntityBuilder.okWithCommonError(e.getMessage());
            }

            olapTable.readLock();
            try {
                resultMap.put("status", 200);
                resultMap.put("size", olapTable.proximateRowCount());
            } finally {
                olapTable.readUnlock();
            }
        } catch (DorisHttpException e) {
            // status code  should conforms to HTTP semantic
            resultMap.put("status", e.getCode().code());
            resultMap.put("exception", e.getMessage());
        }

        return ResponseEntityBuilder.ok(resultMap);
    }
}