feat: add latest smart contract txs materialized view

* feat: add contract_txs materialized view * chore: refresh view on update * chore: fix unit tests * feat: optimize view to include last 50 txs * feat: refresh on microblock updates as well * chore: remove unused var * chore: select only required columns * fix: race condition on refresh and pg notify * chore: return to shorthand or-equal notation * fix: await for pg notification emission * chore: make helper for refreshing views * fix: sql syntax error * chore: fix style for view selection
2026-01-13 08:40:42 +08:00 · 2021-11-23 16:41:01 -06:00
parent e7d8efa9f3
commit 67c453cb6c
5 changed files with 264 additions and 102 deletions
--- a/src/datastore/postgres-notifier.ts
+++ b/src/datastore/postgres-notifier.ts
@@ -70,32 +70,32 @@ export class PgNotifier {
    await this.subscriber.listenTo(this.pgChannelName);
  }

-  public sendBlock(payload: PgBlockNotificationPayload) {
-    this.notify({ type: 'blockUpdate', payload: payload });
+  public async sendBlock(payload: PgBlockNotificationPayload) {
+    await this.notify({ type: 'blockUpdate', payload: payload });
  }

-  public sendMicroblock(payload: PgMicroblockNotificationPayload) {
-    this.notify({ type: 'microblockUpdate', payload: payload });
+  public async sendMicroblock(payload: PgMicroblockNotificationPayload) {
+    await this.notify({ type: 'microblockUpdate', payload: payload });
  }

-  public sendTx(payload: PgTxNotificationPayload) {
-    this.notify({ type: 'txUpdate', payload: payload });
+  public async sendTx(payload: PgTxNotificationPayload) {
+    await this.notify({ type: 'txUpdate', payload: payload });
  }

-  public sendAddress(payload: PgAddressNotificationPayload) {
-    this.notify({ type: 'addressUpdate', payload: payload });
+  public async sendAddress(payload: PgAddressNotificationPayload) {
+    await this.notify({ type: 'addressUpdate', payload: payload });
  }

-  public sendName(payload: PgNameNotificationPayload) {
-    this.notify({ type: 'nameUpdate', payload: payload });
+  public async sendName(payload: PgNameNotificationPayload) {
+    await this.notify({ type: 'nameUpdate', payload: payload });
  }

-  public sendTokenMetadata(payload: PgTokenMetadataNotificationPayload) {
-    this.notify({ type: 'tokenMetadataUpdateQueued', payload: payload });
+  public async sendTokenMetadata(payload: PgTokenMetadataNotificationPayload) {
+    await this.notify({ type: 'tokenMetadataUpdateQueued', payload: payload });
  }

-  public sendTokens(payload: PgTokensNotificationPayload) {
-    this.notify({ type: 'tokensUpdate', payload: payload });
+  public async sendTokens(payload: PgTokensNotificationPayload) {
+    await this.notify({ type: 'tokensUpdate', payload: payload });
  }

  public async close() {
@@ -103,8 +103,8 @@ export class PgNotifier {
    await this.subscriber.close();
  }

-  private notify(notification: PgNotification) {
-    void this.subscriber
+  private async notify(notification: PgNotification) {
+    await this.subscriber
      .notify(this.pgChannelName, { notification: notification })
      .catch(error =>
        logError(`Error sending PgNotifier notification of type: ${notification.type}`, error)
--- a/src/datastore/postgres-store.ts
+++ b/src/datastore/postgres-store.ts
@@ -37,6 +37,8 @@ import {
  pipelineAsync,
  isProdEnv,
  has0xPrefix,
+  isValidPrincipal,
+  isSmartContractTx,
 } from '../helpers';
 import {
  DataStore,
@@ -963,6 +965,7 @@ export class PgDataStore

      const txs: DataStoreTxEventData[] = [];

+      let refreshContractTxsView = false;
      for (const entry of data.txs) {
        // Note: the properties block_hash and burn_block_time are empty here because the anchor block with that data doesn't yet exist.
        const dbTx: DbTx = {
@@ -987,12 +990,16 @@ export class PgDataStore
          names: entry.names.map(e => ({ ...e, registered_at: blockHeight })),
          namespaces: entry.namespaces.map(e => ({ ...e, ready_block: blockHeight })),
        });
+        refreshContractTxsView ||= isSmartContractTx(dbTx, entry.stxEvents);
      }

      await this.insertMicroblockData(client, dbMicroblocks, txs);
-      dbMicroblocks.forEach(microblock =>
-        this.notifier?.sendMicroblock({ microblockHash: microblock.microblock_hash })
-      );
+      if (refreshContractTxsView) {
+        await this.refreshMaterializedView(client, 'latest_contract_txs');
+      }
+      dbMicroblocks.forEach(async microblock => {
+        await this.notifier?.sendMicroblock({ microblockHash: microblock.microblock_hash });
+      });

      // Find any microblocks that have been orphaned by this latest microblock chain tip.
      // This function also checks that each microblock parent hash points to an existing microblock in the db.
@@ -1192,7 +1199,8 @@ export class PgDataStore

      const blocksUpdated = await this.updateBlock(client, data.block);
      if (blocksUpdated !== 0) {
-        let newNftEvents = false;
+        let refreshNftCustodyView = false;
+        let refreshContractTxsView = false;
        for (const minerRewards of data.minerRewards) {
          await this.updateMinerReward(client, minerRewards);
        }
@@ -1207,7 +1215,7 @@ export class PgDataStore
            await this.updateFtEvent(client, entry.tx, ftEvent);
          }
          for (const nftEvent of entry.nftEvents) {
-            newNftEvents = true;
+            refreshNftCustodyView = true;
            await this.updateNftEvent(client, entry.tx, nftEvent);
          }
          for (const smartContract of entry.smartContracts) {
@@ -1219,9 +1227,13 @@ export class PgDataStore
          for (const namespace of entry.namespaces) {
            await this.updateNamespaces(client, entry.tx, namespace);
          }
+          refreshContractTxsView ||= isSmartContractTx(entry.tx, entry.stxEvents);
        }
-        if (newNftEvents && !this.eventReplay) {
-          await client.query(`REFRESH MATERIALIZED VIEW nft_custody`);
+        if (refreshNftCustodyView) {
+          await this.refreshMaterializedView(client, 'nft_custody');
+        }
+        if (refreshContractTxsView) {
+          await this.refreshMaterializedView(client, 'latest_contract_txs');
        }

        const tokenContractDeployments = data.txs
@@ -1251,13 +1263,13 @@ export class PgDataStore
    // Skip sending `PgNotifier` updates altogether if we're in the genesis block since this block is the
    // event replay of the v1 blockchain.
    if ((data.block.block_height > 1 || !isProdEnv) && this.notifier) {
-      this.notifier?.sendBlock({ blockHash: data.block.block_hash });
-      data.txs.forEach(entry => {
-        this.notifier?.sendTx({ txId: entry.tx.tx_id });
+      await this.notifier?.sendBlock({ blockHash: data.block.block_hash });
+      data.txs.forEach(async entry => {
+        await this.notifier?.sendTx({ txId: entry.tx.tx_id });
      });
      this.emitAddressTxUpdates(data);
      for (const tokenMetadataQueueEntry of tokenMetadataQueueEntries) {
-        this.notifier?.sendTokenMetadata({ entry: tokenMetadataQueueEntry });
+        await this.notifier?.sendTokenMetadata({ entry: tokenMetadataQueueEntry });
      }
    }
  }
@@ -1788,7 +1800,7 @@ export class PgDataStore
        [zonefile, validZonefileHash]
      );
    });
-    this.notifier?.sendName({ nameInfo: tx_id });
+    await this.notifier?.sendName({ nameInfo: tx_id });
  }

  private validateZonefileHash(zonefileHash: string) {
@@ -1857,8 +1869,8 @@ export class PgDataStore
          break;
      }
    });
-    addressTxUpdates.forEach((blockHeight, address) => {
-      this.notifier?.sendAddress({
+    addressTxUpdates.forEach(async (blockHeight, address) => {
+      await this.notifier?.sendAddress({
        address: address,
        blockHeight: blockHeight,
      });
@@ -3190,7 +3202,7 @@ export class PgDataStore
      }
    });
    for (const tx of updatedTxs) {
-      this.notifier?.sendTx({ txId: tx.tx_id });
+      await this.notifier?.sendTx({ txId: tx.tx_id });
    }
  }

@@ -3210,7 +3222,7 @@ export class PgDataStore
      updatedTxs = updateResults.rows.map(r => this.parseMempoolTxQueryResult(r));
    });
    for (const tx of updatedTxs) {
-      this.notifier?.sendTx({ txId: tx.tx_id });
+      await this.notifier?.sendTx({ txId: tx.tx_id });
    }
  }

@@ -4649,6 +4661,23 @@ export class PgDataStore
    });
  }

+  /**
+   * Refreshes a Postgres materialized view.
+   * @param client - Pg Client
+   * @param viewName - Materialized view name
+   * @param skipDuringEventReplay - If we should skip refreshing during event replay
+   */
+  async refreshMaterializedView(
+    client: ClientBase,
+    viewName: string,
+    skipDuringEventReplay = true
+  ) {
+    if (this.eventReplay && skipDuringEventReplay) {
+      return;
+    }
+    await client.query(`REFRESH MATERIALIZED VIEW ${viewName}`);
+  }
+
  async getStxBalance({
    stxAddress,
    includeUnanchored,
@@ -5099,35 +5128,55 @@ export class PgDataStore
        atSingleBlock = false;
        queryParams.push(blockHeight);
      }
-      const resultQuery = await client.query<TxQueryResult & { count: number }>(
-        `
-        WITH principal_txs AS (
-          WITH event_txs AS (
-            SELECT tx_id FROM stx_events WHERE stx_events.sender = $1 OR stx_events.recipient = $1
+      const principal = isValidPrincipal(args.stxAddress);
+      if (!principal) {
+        return { results: [], total: 0 };
+      }
+      // Smart contracts with a very high tx volume get frequent requests for the last N tx, where N
+      // is commonly <= 50. We'll query a materialized view if this is the case.
+      const useMaterializedView =
+        principal.type == 'contractAddress' && !atSingleBlock && args.limit + args.offset <= 50;
+      const resultQuery = useMaterializedView
+        ? await client.query<TxQueryResult & { count: number }>(
+            `
+            SELECT ${TX_COLUMNS}, (COUNT(*) OVER())::integer as count
+            FROM latest_contract_txs
+            WHERE contract_id = $1 AND block_height <= $4
+            ORDER BY block_height DESC, microblock_sequence DESC, tx_index DESC
+            LIMIT $2
+            OFFSET $3
+            `,
+            queryParams
          )
-          SELECT *
-          FROM txs
-          WHERE canonical = true AND microblock_canonical = true AND (
-            sender_address = $1 OR
-            token_transfer_recipient_address = $1 OR
-            contract_call_contract_id = $1 OR
-            smart_contract_contract_id = $1
-          )
-          UNION
-          SELECT txs.* FROM txs
-          INNER JOIN event_txs
-          ON txs.tx_id = event_txs.tx_id
-          WHERE txs.canonical = true AND txs.microblock_canonical = true
-        )
-        SELECT ${TX_COLUMNS}, (COUNT(*) OVER())::integer as count
-        FROM principal_txs
-        ${atSingleBlock ? 'WHERE block_height = $4' : 'WHERE block_height <= $4'}
-        ORDER BY block_height DESC, microblock_sequence DESC, tx_index DESC
-        LIMIT $2
-        OFFSET $3
-        `,
-        queryParams
-      );
+        : await client.query<TxQueryResult & { count: number }>(
+            `
+            WITH principal_txs AS (
+              WITH event_txs AS (
+                SELECT tx_id FROM stx_events WHERE stx_events.sender = $1 OR stx_events.recipient = $1
+              )
+              SELECT *
+              FROM txs
+              WHERE canonical = true AND microblock_canonical = true AND (
+                sender_address = $1 OR
+                token_transfer_recipient_address = $1 OR
+                contract_call_contract_id = $1 OR
+                smart_contract_contract_id = $1
+              )
+              UNION
+              SELECT txs.* FROM txs
+              INNER JOIN event_txs
+              ON txs.tx_id = event_txs.tx_id
+              WHERE txs.canonical = true AND txs.microblock_canonical = true
+            )
+            SELECT ${TX_COLUMNS}, (COUNT(*) OVER())::integer as count
+            FROM principal_txs
+            ${atSingleBlock ? 'WHERE block_height = $4' : 'WHERE block_height <= $4'}
+            ORDER BY block_height DESC, microblock_sequence DESC, tx_index DESC
+            LIMIT $2
+            OFFSET $3
+            `,
+            queryParams
+          );
      const count = resultQuery.rowCount > 0 ? resultQuery.rows[0].count : 0;
      const parsed = resultQuery.rows.map(r => this.parseTxQueryResult(r));
      return { results: parsed, total: count };
@@ -6657,7 +6706,7 @@ export class PgDataStore
      );
      return result.rowCount;
    });
-    this.notifier?.sendTokens({ contractID: contract_id });
+    await this.notifier?.sendTokens({ contractID: contract_id });
    return rowCount;
  }

@@ -6703,7 +6752,7 @@ export class PgDataStore
      );
      return result.rowCount;
    });
-    this.notifier?.sendTokens({ contractID: contract_id });
+    await this.notifier?.sendTokens({ contractID: contract_id });
    return rowCount;
  }

@@ -6797,8 +6846,8 @@ export class PgDataStore
      return;
    }
    await this.queryTx(async client => {
-      // Refresh postgres materialized views.
-      await client.query(`REFRESH MATERIALIZED VIEW nft_custody`);
+      await this.refreshMaterializedView(client, 'nft_custody', false);
+      await this.refreshMaterializedView(client, 'latest_contract_txs', false);
    });
  }

--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -16,6 +16,7 @@ import {
  NpmConfigSetLevels,
  SyslogConfigSetLevels,
 } from 'winston/lib/winston/config';
+import { DbStxEvent, DbTx } from './datastore/common';

 export const isDevEnv = process.env.NODE_ENV === 'development';
 export const isTestEnv = process.env.NODE_ENV === 'test';
@@ -956,3 +957,30 @@ export function getSendManyContract(chainId: ChainID) {
      : process.env.TESTNET_SEND_MANY_CONTRACT_ID;
  return contractId;
 }
+
+/**
+ * Determines if a transaction involved a smart contract.
+ * @param dbTx - Transaction DB entry
+ * @param stxEvents - Associated STX Events for this tx
+ * @returns true if tx involved a smart contract, false otherwise
+ */
+export function isSmartContractTx(dbTx: DbTx, stxEvents: DbStxEvent[] = []): boolean {
+  if (
+    dbTx.smart_contract_contract_id ||
+    dbTx.contract_call_contract_id ||
+    isValidContractName(dbTx.sender_address) ||
+    (dbTx.token_transfer_recipient_address &&
+      isValidContractName(dbTx.token_transfer_recipient_address))
+  ) {
+    return true;
+  }
+  for (const stxEvent of stxEvents) {
+    if (
+      (stxEvent.sender && isValidContractName(stxEvent.sender)) ||
+      (stxEvent.recipient && isValidContractName(stxEvent.recipient))
+    ) {
+      return true;
+    }
+  }
+  return false;
+}
--- a/src/migrations/1636741389602_latest_contract_txs.ts
+++ b/src/migrations/1636741389602_latest_contract_txs.ts
@@ -0,0 +1,66 @@
+/* eslint-disable @typescript-eslint/camelcase */
+import { MigrationBuilder, ColumnDefinitions } from 'node-pg-migrate';
+
+export const shorthands: ColumnDefinitions | undefined = undefined;
+
+export async function up(pgm: MigrationBuilder): Promise<void> {
+  pgm.createMaterializedView('latest_contract_txs', {}, `
+    WITH contract_txs AS (
+      SELECT
+        contract_call_contract_id AS contract_id, tx_id,
+        block_height, microblock_sequence, tx_index
+      FROM txs
+      WHERE
+        contract_call_contract_id IS NOT NULL
+        AND canonical = TRUE
+        AND microblock_canonical = TRUE
+      UNION
+      SELECT
+        smart_contract_contract_id AS contract_id, tx_id,
+        block_height, microblock_sequence, tx_index
+      FROM txs
+      WHERE
+        smart_contract_contract_id IS NOT NULL
+        AND canonical = TRUE
+        AND microblock_canonical = TRUE
+      UNION
+      SELECT
+        sender_address AS contract_id, tx_id,
+        block_height, microblock_sequence, tx_index
+      FROM txs
+      WHERE
+        sender_address LIKE '%.%'
+        AND canonical = TRUE
+        AND microblock_canonical = TRUE
+      UNION
+      SELECT
+        token_transfer_recipient_address AS contract_id, tx_id,
+        block_height, microblock_sequence, tx_index
+      FROM txs
+      WHERE
+        token_transfer_recipient_address LIKE '%.%'
+        AND canonical = TRUE
+        AND microblock_canonical = TRUE
+    ),
+    numbered_txs AS (
+      SELECT
+        ROW_NUMBER() OVER (
+          PARTITION BY contract_id
+          ORDER BY block_height DESC, microblock_sequence DESC, tx_index DESC
+        ) AS r,
+        contract_txs.*
+      FROM contract_txs
+    )
+    SELECT numbered_txs.contract_id, txs.*
+    FROM numbered_txs
+    INNER JOIN txs USING (tx_id)
+    WHERE numbered_txs.r <= 50
+  `);
+
+  pgm.createIndex('latest_contract_txs', 'contract_id');
+  pgm.createIndex('latest_contract_txs', [
+    { name: 'block_height', sort: 'DESC' },
+    { name: 'microblock_sequence', sort: 'DESC'},
+    { name: 'tx_index', sort: 'DESC' }
+  ]);
+}
--- a/src/tests/api-tests.ts
+++ b/src/tests/api-tests.ts
@@ -39,6 +39,7 @@ import {
  DbRewardSlotHolder,
  DbMinerReward,
  DbTokenOfferingLocked,
+  DataStoreTxEventData,
 } from '../datastore/common';
 import { startApiServer, ApiServer } from '../api/init';
 import { PgDataStore, cycleMigrations, runMigrations } from '../datastore/postgres-store';
@@ -2901,7 +2902,7 @@ describe('api tests', () => {
      parent_block_hash: '0x5678',
      parent_microblock_hash: '',
      parent_microblock_sequence: 0,
-      block_height: 100123123,
+      block_height: 1,
      burn_block_time: 39486,
      burn_block_hash: '0x1234',
      burn_block_height: 100123123,
@@ -2913,7 +2914,6 @@ describe('api tests', () => {
      execution_cost_write_count: 0,
      execution_cost_write_length: 0,
    };
-    await db.updateBlock(client, block);

    let indexIdIndex = 0;
    const createStxTx = (
@@ -2928,10 +2928,10 @@ describe('api tests', () => {
        anchor_mode: 3,
        nonce: 0,
        raw_tx: Buffer.alloc(0),
-        index_block_hash: '0x5432',
-        block_hash: '0x9876',
-        block_height: 68456,
-        burn_block_time: 1594647994,
+        index_block_hash: block.index_block_hash,
+        block_hash: block.block_hash,
+        block_height: block.block_height,
+        burn_block_time: block.burn_block_time,
        parent_burn_block_time: 1626122935,
        type_id: DbTxTypeId.TokenTransfer,
        token_transfer_amount: BigInt(amount),
@@ -2969,9 +2969,6 @@ describe('api tests', () => {
      createStxTx(testContractAddr, testAddr4, 15),
      createStxTx(testAddr2, testAddr4, 35),
    ];
-    for (const tx of txs) {
-      await db.updateTx(client, tx);
-    }

    const tx: DbTx = {
      tx_id: '0x1234',
@@ -2979,10 +2976,10 @@ describe('api tests', () => {
      anchor_mode: 3,
      nonce: 0,
      raw_tx: Buffer.alloc(0),
-      index_block_hash: '0x5432',
-      block_hash: '0x9876',
-      block_height: 68456,
-      burn_block_time: 1594647994,
+      index_block_hash: block.index_block_hash,
+      block_hash: block.block_hash,
+      block_height: block.block_height,
+      burn_block_time: block.burn_block_time,
      parent_burn_block_time: 1626122935,
      type_id: DbTxTypeId.Coinbase,
      coinbase_payload: Buffer.from('coinbase hi'),
@@ -3035,9 +3032,6 @@ describe('api tests', () => {
      createStxEvent(testContractAddr, testAddr4, 15),
      createStxEvent(testAddr2, testAddr4, 35),
    ];
-    for (const event of events) {
-      await db.updateStxEvent(client, tx, event);
-    }

    const createFtEvent = (
      sender: string,
@@ -3077,9 +3071,6 @@ describe('api tests', () => {
      createFtEvent(testAddr1, testAddr2, 'cash', 500_000),
      createFtEvent(testAddr2, testAddr1, 'tendies', 1_000_000),
    ];
-    for (const event of ftEvents) {
-      await db.updateFtEvent(client, tx, event);
-    }

    const createNFtEvents = (
      sender: string,
@@ -3123,14 +3114,42 @@ describe('api tests', () => {
      createNFtEvents(testAddr1, testAddr2, 'cash', 500),
      createNFtEvents(testAddr2, testAddr1, 'tendies', 100),
    ];
-    for (const event of nftEvents.flat()) {
-      await db.updateNftEvent(client, tx, event);
-    }
+
+    const dataStoreTxs = txs.map(dbTx => {
+      return {
+        tx: dbTx,
+        stxLockEvents: [],
+        stxEvents: [],
+        ftEvents: [],
+        nftEvents: [],
+        contractLogEvents: [],
+        smartContracts: [],
+        names: [],
+        namespaces: [],
+      } as DataStoreTxEventData;
+    });
+    dataStoreTxs.push({
+      tx: tx,
+      stxLockEvents: [],
+      stxEvents: events,
+      ftEvents: ftEvents,
+      nftEvents: nftEvents.flat(),
+      contractLogEvents: [],
+      smartContracts: [],
+      names: [],
+      namespaces: [],
+    });
+    await db.update({
+      block: block,
+      microblocks: [],
+      minerRewards: [],
+      txs: dataStoreTxs,
+    });

    const tokenOfferingLocked: DbTokenOfferingLocked = {
      address: testAddr2,
      value: BigInt(4139394444),
-      block: 33477,
+      block: 1,
    };
    await db.updateBatchTokenOfferingLocked(client, [tokenOfferingLocked]);

@@ -3170,7 +3189,7 @@ describe('api tests', () => {
        unlock_schedule: [
          {
            amount: '4139394444',
-            block_height: 33477,
+            block_height: 1,
          },
        ],
      },
@@ -3209,7 +3228,7 @@ describe('api tests', () => {
    const tokenLocked: DbTokenOfferingLocked = {
      address: testContractAddr,
      value: BigInt(4139391122),
-      block: 20477,
+      block: 1,
    };

    await db.updateBatchTokenOfferingLocked(client, [tokenLocked]);
@@ -3235,7 +3254,7 @@ describe('api tests', () => {
        unlock_schedule: [
          {
            amount: '4139391122',
-            block_height: 20477,
+            block_height: 1,
          },
        ],
      },
@@ -3377,10 +3396,10 @@ describe('api tests', () => {
          sponsored: false,
          post_condition_mode: 'allow',
          post_conditions: [],
-          block_hash: '0x9876',
-          block_height: 68456,
-          burn_block_time: 1594647994,
-          burn_block_time_iso: '2020-07-13T13:46:34.000Z',
+          block_hash: '0x1234',
+          block_height: 1,
+          burn_block_time: 39486,
+          burn_block_time_iso: '1970-01-01T10:58:06.000Z',
          canonical: true,
          microblock_canonical: true,
          microblock_hash: '',
@@ -3418,10 +3437,10 @@ describe('api tests', () => {
          sponsored: false,
          post_condition_mode: 'allow',
          post_conditions: [],
-          block_hash: '0x9876',
-          block_height: 68456,
-          burn_block_time: 1594647994,
-          burn_block_time_iso: '2020-07-13T13:46:34.000Z',
+          block_hash: '0x1234',
+          block_height: 1,
+          burn_block_time: 39486,
+          burn_block_time_iso: '1970-01-01T10:58:06.000Z',
          canonical: true,
          microblock_canonical: true,
          microblock_hash: '',
@@ -3459,10 +3478,10 @@ describe('api tests', () => {
          sponsored: false,
          post_condition_mode: 'allow',
          post_conditions: [],
-          block_hash: '0x9876',
-          block_height: 68456,
-          burn_block_time: 1594647994,
-          burn_block_time_iso: '2020-07-13T13:46:34.000Z',
+          block_hash: '0x1234',
+          block_height: 1,
+          burn_block_time: 39486,
+          burn_block_time_iso: '1970-01-01T10:58:06.000Z',
          canonical: true,
          microblock_canonical: true,
          microblock_hash: '',