Refactor api pagination

api/account.go

@@ -5,7 +5,6 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/hermeznetwork/hermez-node/apitypes"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -49,7 +48,7 @@ func (a *API) getAccounts(c *gin.Context) {
 	}
 
 	// Fetch Accounts from historyDB
-	apiAccounts, pagination, err := a.h.GetAccountsAPI(tokenIDs, addr, bjj, fromItem, limit, order)
+	apiAccounts, pendingItems, err := a.h.GetAccountsAPI(tokenIDs, addr, bjj, fromItem, limit, order)
 	if err != nil {
 		retSQLErr(err, c)
 		return
@@ -72,11 +71,11 @@ func (a *API) getAccounts(c *gin.Context) {
 
 	// Build succesfull response
 	type accountResponse struct {
-		Accounts   []historydb.AccountAPI `json:"accounts"`
-		Pagination *db.Pagination         `json:"pagination"`
+		Accounts     []historydb.AccountAPI `json:"accounts"`
+		PendingItems uint64                 `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &accountResponse{
-		Accounts:   apiAccounts,
-		Pagination: pagination,
+		Accounts:     apiAccounts,
+		PendingItems: pendingItems,
 	})
 }

api/account_test.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/hermeznetwork/hermez-node/apitypes"
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
@@ -25,10 +24,18 @@ type testAccount struct {
 }
 
 type testAccountsResponse struct {
-	Accounts   []testAccount  `json:"accounts"`
-	Pagination *db.Pagination `json:"pagination"`
+	Accounts     []testAccount `json:"accounts"`
+	PendingItems uint64        `json:"pendingItems"`
 }
 
+func (t testAccountsResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Accounts[len(t.Accounts)-1].ItemID
+	return pendingItems, lastItemID
+}
+
+func (t *testAccountsResponse) Len() int { return len(t.Accounts) }
+
 func genTestAccounts(accounts []common.Account, tokens []historydb.TokenWithUSD) []testAccount {
 	tAccounts := []testAccount{}
 	for x, account := range accounts {
@@ -47,19 +54,6 @@ func genTestAccounts(accounts []common.Account, tokens []historydb.TokenWithUSD)
 	return tAccounts
 }
 
-func (t *testAccountsResponse) GetPagination() *db.Pagination {
-	if t.Accounts[0].ItemID < t.Accounts[len(t.Accounts)-1].ItemID {
-		t.Pagination.FirstReturnedItem = t.Accounts[0].ItemID
-		t.Pagination.LastReturnedItem = t.Accounts[len(t.Accounts)-1].ItemID
-	} else {
-		t.Pagination.LastReturnedItem = t.Accounts[0].ItemID
-		t.Pagination.FirstReturnedItem = t.Accounts[len(t.Accounts)-1].ItemID
-	}
-	return t.Pagination
-}
-
-func (t *testAccountsResponse) Len() int { return len(t.Accounts) }
-
 func TestGetAccounts(t *testing.T) {
 	endpoint := apiURL + "accounts"
 	fetchedAccounts := []testAccount{}

api/api_test.go

@@ -28,6 +28,13 @@ import (
 	"github.com/iden3/go-iden3-crypto/babyjub"
 )
 
+// Pendinger is an interface that allows getting last returned item ID and PendingItems to be used for building fromItem
+// when testing paginated endpoints.
+type Pendinger interface {
+	GetPending() (pendingItems, lastItemID uint64)
+	Len() int
+}
+
 const apiPort = ":4010"
 const apiURL = "http://localhost" + apiPort + "/"
 
@@ -339,41 +346,52 @@ func TestMain(m *testing.M) {
 
 func doGoodReqPaginated(
 	path, order string,
-	iterStruct db.Paginationer,
+	iterStruct Pendinger,
 	appendIter func(res interface{}),
 ) error {
-	next := -1
+	var next uint64
+	firstIte := true
+	expectedTotal := 0
+	totalReceived := 0
 	for {
-		// Call API to get this iteration items
+		// Calculate fromItem
 		iterPath := path
-		if next == -1 && order == historydb.OrderDesc {
-			// Fetch first item in reverse order
-			iterPath += "99999"
-		} else {
-			// Fetch from next item or 0 if it's ascending order
-			if next == -1 {
-				next = 0
+		if firstIte {
+			if order == historydb.OrderDesc {
+				// Fetch first item in reverse order
+				iterPath += "99999" // Asumption that for testing there won't be any itemID > 99999
+			} else {
+				iterPath += "0"
 			}
-			iterPath += strconv.Itoa(next)
+		} else {
+			iterPath += strconv.Itoa(int(next))
 		}
+		// Call API to get this iteration items
 		if err := doGoodReq("GET", iterPath+"&order="+order, nil, iterStruct); err != nil {
 			return err
 		}
 		appendIter(iterStruct)
 		// Keep iterating?
-		pag := iterStruct.GetPagination()
-		if order == historydb.OrderAsc {
-			if pag.LastReturnedItem == pag.LastItem { // No
-				break
-			} else { // Yes
-				next = int(pag.LastReturnedItem + 1)
-			}
+		remaining, lastID := iterStruct.GetPending()
+		if remaining == 0 {
+			break
+		}
+		if order == historydb.OrderDesc {
+			next = lastID - 1
 		} else {
-			if pag.FirstReturnedItem == pag.FirstItem { // No
-				break
-			} else { // Yes
-				next = int(pag.FirstReturnedItem - 1)
-			}
+			next = lastID + 1
+		}
+		// Check that the expected amount of items is consistent across iterations
+		totalReceived += iterStruct.Len()
+		if firstIte {
+			firstIte = false
+			expectedTotal = totalReceived + int(remaining)
+		}
+		if expectedTotal != totalReceived+int(remaining) {
+			panic(fmt.Sprintf(
+				"pagination error, totalReceived + remaining should be %d, but is %d",
+				expectedTotal, totalReceived+int(remaining),
+			))
 		}
 	}
 	return nil

api/batch.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -43,7 +42,7 @@ func (a *API) getBatches(c *gin.Context) {
 		return
 	}
 	// Fetch batches from historyDB
-	batches, pagination, err := a.h.GetBatchesAPI(
+	batches, pendingItems, err := a.h.GetBatchesAPI(
 		minBatchNum, maxBatchNum, slotNum, forgerAddr, fromItem, limit, order,
 	)
 	if err != nil {
@@ -53,12 +52,12 @@ func (a *API) getBatches(c *gin.Context) {
 
 	// Build succesfull response
 	type batchesResponse struct {
-		Batches    []historydb.BatchAPI `json:"batches"`
-		Pagination *db.Pagination       `json:"pagination"`
+		Batches      []historydb.BatchAPI `json:"batches"`
+		PendingItems uint64               `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &batchesResponse{
-		Batches:    batches,
-		Pagination: pagination,
+		Batches:      batches,
+		PendingItems: pendingItems,
 	})
 }
 

api/batch_test.go

@@ -8,7 +8,6 @@ import (
 
 	ethCommon "github.com/ethereum/go-ethereum/common"
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
@@ -30,19 +29,14 @@ type testBatch struct {
 	SlotNum       int64                     `json:"slotNum"`
 }
 type testBatchesResponse struct {
-	Batches    []testBatch    `json:"batches"`
-	Pagination *db.Pagination `json:"pagination"`
+	Batches      []testBatch `json:"batches"`
+	PendingItems uint64      `json:"pendingItems"`
 }
 
-func (t testBatchesResponse) GetPagination() *db.Pagination {
-	if t.Batches[0].ItemID < t.Batches[len(t.Batches)-1].ItemID {
-		t.Pagination.FirstReturnedItem = t.Batches[0].ItemID
-		t.Pagination.LastReturnedItem = t.Batches[len(t.Batches)-1].ItemID
-	} else {
-		t.Pagination.LastReturnedItem = t.Batches[0].ItemID
-		t.Pagination.FirstReturnedItem = t.Batches[len(t.Batches)-1].ItemID
-	}
-	return t.Pagination
+func (t testBatchesResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Batches[len(t.Batches)-1].ItemID
+	return pendingItems, lastItemID
 }
 
 func (t testBatchesResponse) Len() int {

api/bids.go

@@ -5,7 +5,6 @@ import (
 	"net/http"
 
 	"github.com/gin-gonic/gin"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -26,7 +25,7 @@ func (a *API) getBids(c *gin.Context) {
 		return
 	}
 
-	bids, pagination, err := a.h.GetBidsAPI(
+	bids, pendingItems, err := a.h.GetBidsAPI(
 		slotNum, bidderAddr, fromItem, limit, order,
 	)
 
@@ -37,11 +36,11 @@ func (a *API) getBids(c *gin.Context) {
 
 	// Build succesfull response
 	type bidsResponse struct {
-		Bids       []historydb.BidAPI `json:"bids"`
-		Pagination *db.Pagination     `json:"pagination"`
+		Bids         []historydb.BidAPI `json:"bids"`
+		PendingItems uint64             `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &bidsResponse{
-		Bids:       bids,
-		Pagination: pagination,
+		Bids:         bids,
+		PendingItems: pendingItems,
 	})
 }

api/bids_test.go

@@ -7,7 +7,6 @@ import (
 
 	ethCommon "github.com/ethereum/go-ethereum/common"
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
@@ -25,19 +24,14 @@ type testBid struct {
 }
 
 type testBidsResponse struct {
-	Bids       []testBid      `json:"bids"`
-	Pagination *db.Pagination `json:"pagination"`
+	Bids         []testBid `json:"bids"`
+	PendingItems uint64    `json:"pendingItems"`
 }
 
-func (t testBidsResponse) GetPagination() *db.Pagination {
-	if t.Bids[0].ItemID < t.Bids[len(t.Bids)-1].ItemID {
-		t.Pagination.FirstReturnedItem = t.Bids[0].ItemID
-		t.Pagination.LastReturnedItem = t.Bids[len(t.Bids)-1].ItemID
-	} else {
-		t.Pagination.LastReturnedItem = t.Bids[0].ItemID
-		t.Pagination.FirstReturnedItem = t.Bids[len(t.Bids)-1].ItemID
-	}
-	return t.Pagination
+func (t testBidsResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Bids[len(t.Bids)-1].ItemID
+	return pendingItems, lastItemID
 }
 
 func (t testBidsResponse) Len() int {

api/coordinator.go

@@ -4,7 +4,6 @@ import (
 	"net/http"
 
 	"github.com/gin-gonic/gin"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -39,7 +38,7 @@ func (a *API) getCoordinators(c *gin.Context) {
 	}
 
 	// Fetch coordinators from historyDB
-	coordinators, pagination, err := a.h.GetCoordinatorsAPI(fromItem, limit, order)
+	coordinators, pendingItems, err := a.h.GetCoordinatorsAPI(fromItem, limit, order)
 	if err != nil {
 		retSQLErr(err, c)
 		return
@@ -48,10 +47,10 @@ func (a *API) getCoordinators(c *gin.Context) {
 	// Build succesfull response
 	type coordinatorsResponse struct {
 		Coordinators []historydb.CoordinatorAPI `json:"coordinators"`
-		Pagination   *db.Pagination             `json:"pagination"`
+		PendingItems uint64                     `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &coordinatorsResponse{
 		Coordinators: coordinators,
-		Pagination:   pagination,
+		PendingItems: pendingItems,
 	})
 }

api/coordinator_test.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"testing"
 
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
@@ -12,18 +11,13 @@ import (
 
 type testCoordinatorsResponse struct {
 	Coordinators []historydb.CoordinatorAPI `json:"coordinators"`
-	Pagination   *db.Pagination             `json:"pagination"`
+	PendingItems uint64                     `json:"pendingItems"`
 }
 
-func (t *testCoordinatorsResponse) GetPagination() *db.Pagination {
-	if t.Coordinators[0].ItemID < t.Coordinators[len(t.Coordinators)-1].ItemID {
-		t.Pagination.FirstReturnedItem = t.Coordinators[0].ItemID
-		t.Pagination.LastReturnedItem = t.Coordinators[len(t.Coordinators)-1].ItemID
-	} else {
-		t.Pagination.LastReturnedItem = t.Coordinators[0].ItemID
-		t.Pagination.FirstReturnedItem = t.Coordinators[len(t.Coordinators)-1].ItemID
-	}
-	return t.Pagination
+func (t testCoordinatorsResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Coordinators[len(t.Coordinators)-1].ItemID
+	return pendingItems, lastItemID
 }
 
 func (t *testCoordinatorsResponse) Len() int { return len(t.Coordinators) }

api/exits.go

@@ -4,7 +4,6 @@ import (
 	"net/http"
 
 	"github.com/gin-gonic/gin"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -36,7 +35,7 @@ func (a *API) getExits(c *gin.Context) {
 	}
 
 	// Fetch exits from historyDB
-	exits, pagination, err := a.h.GetExitsAPI(
+	exits, pendingItems, err := a.h.GetExitsAPI(
 		addr, bjj, tokenID, idx, batchNum, onlyPendingWithdraws, fromItem, limit, order,
 	)
 	if err != nil {
@@ -46,12 +45,12 @@ func (a *API) getExits(c *gin.Context) {
 
 	// Build succesfull response
 	type exitsResponse struct {
-		Exits      []historydb.ExitAPI `json:"exits"`
-		Pagination *db.Pagination      `json:"pagination"`
+		Exits        []historydb.ExitAPI `json:"exits"`
+		PendingItems uint64              `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &exitsResponse{
-		Exits:      exits,
-		Pagination: pagination,
+		Exits:        exits,
+		PendingItems: pendingItems,
 	})
 }
 

api/exits_test.go

@@ -5,7 +5,6 @@ import (
 	"testing"
 
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
@@ -36,19 +35,14 @@ type testExit struct {
 }
 
 type testExitsResponse struct {
-	Exits      []testExit     `json:"exits"`
-	Pagination *db.Pagination `json:"pagination"`
+	Exits        []testExit `json:"exits"`
+	PendingItems uint64     `json:"pendingItems"`
 }
 
-func (t *testExitsResponse) GetPagination() *db.Pagination {
-	if t.Exits[0].ItemID < t.Exits[len(t.Exits)-1].ItemID {
-		t.Pagination.FirstReturnedItem = t.Exits[0].ItemID
-		t.Pagination.LastReturnedItem = t.Exits[len(t.Exits)-1].ItemID
-	} else {
-		t.Pagination.LastReturnedItem = t.Exits[0].ItemID
-		t.Pagination.FirstReturnedItem = t.Exits[len(t.Exits)-1].ItemID
-	}
-	return t.Pagination
+func (t testExitsResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Exits[len(t.Exits)-1].ItemID
+	return pendingItems, lastItemID
 }
 
 func (t *testExitsResponse) Len() int {

api/slots.go

@@ -7,7 +7,6 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -49,18 +48,6 @@ func (a *API) isOpenAuction(currentBlock, slotNum int64, auctionVars common.Auct
 	return false
 }
 
-func getPagination(totalItems uint64, minSlotNum, maxSlotNum *int64) *db.Pagination {
-	// itemID is slotNum
-	firstItem := *minSlotNum
-	lastItem := *maxSlotNum
-	pagination := &db.Pagination{
-		TotalItems: totalItems,
-		FirstItem:  uint64(firstItem),
-		LastItem:   uint64(lastItem),
-	}
-	return pagination
-}
-
 func (a *API) newSlotAPI(slotNum, currentBlockNum int64, bid *historydb.BidAPI, auctionVars *common.AuctionVariables) SlotAPI {
 	firstBlock, lastBlock := a.getFirstLastBlock(slotNum)
 	openAuction := a.isOpenAuction(currentBlockNum, slotNum, *auctionVars)
@@ -141,34 +128,35 @@ func (a *API) getSlot(c *gin.Context) {
 	c.JSON(http.StatusOK, slot)
 }
 
-func getLimits(minSlotNum, maxSlotNum *int64, fromItem, limit *uint, order string) (int64, int64) {
-	var minLim, maxLim int64
-	if fromItem != nil {
-		if order == historydb.OrderAsc {
-			if int64(*fromItem) > *minSlotNum {
-				minLim = int64(*fromItem)
-			} else {
-				minLim = *minSlotNum
-			}
-			if (minLim + int64(*limit-1)) < *maxSlotNum {
-				maxLim = minLim + int64(*limit-1)
-			} else {
-				maxLim = *maxSlotNum
-			}
+func getLimits(
+	minSlotNum, maxSlotNum int64, fromItem, limit *uint, order string,
+) (minLimit, maxLimit int64, pendingItems uint64) {
+	if order == historydb.OrderAsc {
+		if fromItem != nil && int64(*fromItem) > minSlotNum {
+			minLimit = int64(*fromItem)
 		} else {
-			if int64(*fromItem) < *maxSlotNum {
-				maxLim = int64(*fromItem)
-			} else {
-				maxLim = *maxSlotNum
-			}
-			if (maxLim - int64(*limit-1)) < *minSlotNum {
-				minLim = *minSlotNum
-			} else {
-				minLim = maxLim - int64(*limit-1)
-			}
+			minLimit = minSlotNum
+		}
+		if limit != nil && (minLimit+int64(*limit-1)) < maxSlotNum {
+			maxLimit = minLimit + int64(*limit-1)
+		} else {
+			maxLimit = maxSlotNum
+		}
+		pendingItems = uint64(maxSlotNum - maxLimit)
+	} else {
+		if fromItem != nil && int64(*fromItem) < maxSlotNum {
+			maxLimit = int64(*fromItem)
+		} else {
+			maxLimit = maxSlotNum
 		}
+		if limit != nil && (maxLimit-int64(*limit-1)) < minSlotNum {
+			minLimit = minSlotNum
+		} else {
+			minLimit = maxLimit - int64(*limit-1)
+		}
+		pendingItems = uint64(-(minSlotNum - minLimit))
 	}
-	return minLim, maxLim
+	return minLimit, maxLimit, pendingItems
 }
 
 func getLimitsWithAddr(minSlotNum, maxSlotNum *int64, fromItem, limit *uint, order string) (int64, int64) {
@@ -262,29 +250,22 @@ func (a *API) getSlots(c *gin.Context) {
 	// Get bids and pagination according to filters
 	var slotMinLim, slotMaxLim int64
 	var bids []historydb.BidAPI
-	var pag *db.Pagination
-	totalItems := uint64(0)
+	var pendingItems uint64
 	if wonByEthereumAddress == nil {
-		slotMinLim, slotMaxLim = getLimits(minSlotNum, maxSlotNum, fromItem, limit, order)
+		slotMinLim, slotMaxLim, pendingItems = getLimits(*minSlotNum, *maxSlotNum, fromItem, limit, order)
 		// Get best bids in range maxSlotNum - minSlotNum
 		bids, _, err = a.h.GetBestBidsAPI(&slotMinLim, &slotMaxLim, wonByEthereumAddress, nil, order)
 		if err != nil && err != sql.ErrNoRows {
 			retSQLErr(err, c)
 			return
 		}
-		totalItems = uint64(*maxSlotNum) - uint64(*minSlotNum) + 1
 	} else {
 		slotMinLim, slotMaxLim = getLimitsWithAddr(minSlotNum, maxSlotNum, fromItem, limit, order)
-		bids, pag, err = a.h.GetBestBidsAPI(&slotMinLim, &slotMaxLim, wonByEthereumAddress, limit, order)
+		bids, pendingItems, err = a.h.GetBestBidsAPI(&slotMinLim, &slotMaxLim, wonByEthereumAddress, limit, order)
 		if err != nil && err != sql.ErrNoRows {
 			retSQLErr(err, c)
 			return
 		}
-		if len(bids) > 0 {
-			totalItems = uint64(pag.TotalItems)
-			*maxSlotNum = int64(pag.LastItem)
-			*minSlotNum = int64(pag.FirstItem)
-		}
 	}
 
 	// Build the slot information with previous bids
@@ -336,11 +317,11 @@ func (a *API) getSlots(c *gin.Context) {
 
 	// Build succesfull response
 	type slotsResponse struct {
-		Slots      []SlotAPI      `json:"slots"`
-		Pagination *db.Pagination `json:"pagination"`
+		Slots        []SlotAPI `json:"slots"`
+		PendingItems uint64    `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &slotsResponse{
-		Slots:      slots,
-		Pagination: getPagination(totalItems, minSlotNum, maxSlotNum),
+		Slots:        slots,
+		PendingItems: pendingItems,
 	})
 }

api/slots_test.go

@@ -6,14 +6,13 @@ import (
 	"testing"
 
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
 )
 
 type testSlot struct {
-	ItemID      int      `json:"itemId"`
+	ItemID      uint64   `json:"itemId"`
 	SlotNum     int64    `json:"slotNum"`
 	FirstBlock  int64    `json:"firstBlock"`
 	LastBlock   int64    `json:"lastBlock"`
@@ -22,19 +21,14 @@ type testSlot struct {
 }
 
 type testSlotsResponse struct {
-	Slots      []testSlot     `json:"slots"`
-	Pagination *db.Pagination `json:"pagination"`
+	Slots        []testSlot `json:"slots"`
+	PendingItems uint64     `json:"pendingItems"`
 }
 
-func (t testSlotsResponse) GetPagination() *db.Pagination {
-	if t.Slots[0].ItemID < t.Slots[len(t.Slots)-1].ItemID {
-		t.Pagination.FirstReturnedItem = uint64(t.Slots[0].ItemID)
-		t.Pagination.LastReturnedItem = uint64(t.Slots[len(t.Slots)-1].ItemID)
-	} else {
-		t.Pagination.LastReturnedItem = uint64(t.Slots[0].ItemID)
-		t.Pagination.FirstReturnedItem = uint64(t.Slots[len(t.Slots)-1].ItemID)
-	}
-	return t.Pagination
+func (t testSlotsResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Slots[len(t.Slots)-1].ItemID
+	return pendingItems, lastItemID
 }
 
 func (t testSlotsResponse) Len() int {

api/swagger.yml

@@ -17,7 +17,9 @@ info:
     * `order`: all pginated items are ordered chronologicaly. However the specific fields to guarantee this order depend on each endpoint. For this purpose, `itemId` is used (itemId follows ascending chronological order except for unforged L1 user transactions). If the parameter is not provided, ascending order will be used by default. 
     * `limit`: maximum amount of items to include in each response. Default is 20, maximum 2049.
     
-    Responses for those endpoint will always include a `pagination` object. This object includes the total amount of items that the endpoint will return at a given time with the given filters. Apart from that, it also includes the `itemId` of the last and first items that will be returned (not in a single response but within the total items). These two properties can be used to know when to stop querying. 
+    Responses for those endpoint will always include a `pendingItems` property. This property includes the amount of items that are not fetched yet. his can be used to:
+    * Calculate the amount of items that match the filters: `totalItems = length(alreadyFetchedItems) + pendingItems`
+    * Know when all items have been fetched: `if pendingItems == 0 {/* all items have been fetched */}`
 
     #### Reorgs and safetyness
 
@@ -1739,11 +1741,11 @@ components:
           description: List of history transactions.
           items: 
             $ref: '#/components/schemas/HistoryTransaction'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
       required:
         - transactions
-        - pagination
+        - pendingItems
       additionalProperties: false
     EthBlockNum:
       type: integer
@@ -1877,12 +1879,12 @@ components:
           description: List of batches.
           items:
             $ref: '#/components/schemas/Batch'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
       additionalProperties: false
       required:
         - batches
-        - pagination
+        - pendingItems
     Coordinator:
       type: object
       properties:
@@ -1914,12 +1916,12 @@ components:
           description: List of coordinators.
           items: 
             $ref: '#/components/schemas/Coordinator'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
       additionalProperties: false
       required:
         - coordinators
-        - pagination
+        - pendingItems
     Bid:
       type: object
       description: Tokens placed in an auction by a coordinator to gain the right to forge batches during a specific slot.
@@ -1958,12 +1960,12 @@ components:
           description: List of bids.
           items: 
             $ref: '#/components/schemas/Bid'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
       additionalProperties: false
       require:
         - bids
-        - pagination
+        - pendingItems
     RecommendedFee:  
       type: object
       description: Fee that the coordinator recommends per transaction in USD.
@@ -2042,8 +2044,8 @@ components:
           description: List of tokens.
           items: 
             $ref: '#/components/schemas/Token'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
     Exit:
       type: object
       description: Exit tree leaf. It Contains the necessary information to perform a withdrawal.
@@ -2135,11 +2137,11 @@ components:
           description: List of exits.
           items: 
             $ref: '#/components/schemas/Exit'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'   
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'   
       required:
           - exits
-          - pagination
+          - pendingItems
       additionalProperties: false 
     Account:
       type: object
@@ -2176,12 +2178,12 @@ components:
           description: List of accounts.
           items: 
             $ref: '#/components/schemas/Account'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
       additionalProperties: false
       required:
         - accounts
-        - pagination
+        - pendingItems
     Slot:
       type: object
       description: Slot information.
@@ -2255,12 +2257,12 @@ components:
             allOf:
                 - $ref: '#/components/schemas/Slot'
                 - description: Last synchronized Etherum block.
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
       additionalProperties: false
       require:
         - slots
-        - pagination
+        - pendingItems
     NextForger:
       type: object
       description: Coordinator information along with the scheduled forging period
@@ -2289,8 +2291,8 @@ components:
           description: List of next coordinators to forge.
           items: 
             $ref: '#/components/schemas/NextForger'
-        pagination:
-          $ref: '#/components/schemas/PaginationInfo'
+        pendingItems:
+          $ref: '#/components/schemas/PendingItems'
     State:
       type: object
       description: Gobal variables of the network
@@ -2517,22 +2519,10 @@ components:
         - auction
         - withdrawalDelayer
         - recomendedFee 
-    PaginationInfo:
-      type: object
-      description: Give pagination information
-      properties:
-        totalItems:
-          type: integer
-          description: Amount of items that the endpoint can return given the filters and the current state of the database.
-          example: 2048
-        firstItem:
-          type: integer
-          description: The smallest itemId that the endpoint will return with the given filters.
-          example: 50
-        lastItem:
-          type: integer
-          description: The greatest itemId that the endpoint will return with the given filters.
-          example: 2130
+    PendingItems:
+      type: integer
+      description: Amount of items that will be returned in subsequent calls to the endpoint, as long as they are done with same filters. When the value is 0 it means that all items have been sent.
+      example: 15
     Config:
       type: object
       description: Configuration parameters of the different smart contracts that power the Hermez network.

api/token.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -46,7 +45,7 @@ func (a *API) getTokens(c *gin.Context) {
 		return
 	}
 	// Fetch exits from historyDB
-	tokens, pagination, err := a.h.GetTokens(
+	tokens, pendingItems, err := a.h.GetTokens(
 		tokenIDs, symbols, name, fromItem, limit, order,
 	)
 	if err != nil {
@@ -56,11 +55,11 @@ func (a *API) getTokens(c *gin.Context) {
 
 	// Build succesfull response
 	type tokensResponse struct {
-		Tokens     []historydb.TokenWithUSD `json:"tokens"`
-		Pagination *db.Pagination           `json:"pagination"`
+		Tokens       []historydb.TokenWithUSD `json:"tokens"`
+		PendingItems uint64                   `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &tokensResponse{
-		Tokens:     tokens,
-		Pagination: pagination,
+		Tokens:       tokens,
+		PendingItems: pendingItems,
 	})
 }

api/token_test.go

@@ -5,7 +5,6 @@ import (
 	"strconv"
 	"testing"
 
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/mitchellh/copystructure"
 	"github.com/stretchr/testify/assert"
@@ -13,19 +12,14 @@ import (
 )
 
 type testTokensResponse struct {
-	Tokens     []historydb.TokenWithUSD `json:"tokens"`
-	Pagination *db.Pagination           `json:"pagination"`
+	Tokens       []historydb.TokenWithUSD `json:"tokens"`
+	PendingItems uint64                   `json:"pendingItems"`
 }
 
-func (t *testTokensResponse) GetPagination() *db.Pagination {
-	if t.Tokens[0].ItemID < t.Tokens[len(t.Tokens)-1].ItemID {
-		t.Pagination.FirstReturnedItem = t.Tokens[0].ItemID
-		t.Pagination.LastReturnedItem = t.Tokens[len(t.Tokens)-1].ItemID
-	} else {
-		t.Pagination.LastReturnedItem = t.Tokens[0].ItemID
-		t.Pagination.FirstReturnedItem = t.Tokens[len(t.Tokens)-1].ItemID
-	}
-	return t.Pagination
+func (t testTokensResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Tokens[len(t.Tokens)-1].ItemID
+	return pendingItems, lastItemID
 }
 
 func (t *testTokensResponse) Len() int {

api/txshistory.go

@@ -4,7 +4,6 @@ import (
 	"net/http"
 
 	"github.com/gin-gonic/gin"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 )
 
@@ -35,7 +34,7 @@ func (a *API) getHistoryTxs(c *gin.Context) {
 	}
 
 	// Fetch txs from historyDB
-	txs, pagination, err := a.h.GetHistoryTxs(
+	txs, pendingItems, err := a.h.GetHistoryTxs(
 		addr, bjj, tokenID, idx, batchNum, txType, fromItem, limit, order,
 	)
 	if err != nil {
@@ -45,12 +44,12 @@ func (a *API) getHistoryTxs(c *gin.Context) {
 
 	// Build succesfull response
 	type txsResponse struct {
-		Txs        []historydb.TxAPI `json:"transactions"`
-		Pagination *db.Pagination    `json:"pagination"`
+		Txs          []historydb.TxAPI `json:"transactions"`
+		PendingItems uint64            `json:"pendingItems"`
 	}
 	c.JSON(http.StatusOK, &txsResponse{
-		Txs:        txs,
-		Pagination: pagination,
+		Txs:          txs,
+		PendingItems: pendingItems,
 	})
 }
 

api/txshistory_test.go

@@ -9,7 +9,6 @@ import (
 
 	"github.com/hermeznetwork/hermez-node/apitypes"
 	"github.com/hermeznetwork/hermez-node/common"
-	"github.com/hermeznetwork/hermez-node/db"
 	"github.com/hermeznetwork/hermez-node/db/historydb"
 	"github.com/hermeznetwork/hermez-node/test"
 	"github.com/mitchellh/copystructure"
@@ -53,19 +52,14 @@ type testTx struct {
 }
 
 type testTxsResponse struct {
-	Txs        []testTx       `json:"transactions"`
-	Pagination *db.Pagination `json:"pagination"`
+	Txs          []testTx `json:"transactions"`
+	PendingItems uint64   `json:"pendingItems"`
 }
 
-func (t testTxsResponse) GetPagination() *db.Pagination {
-	if t.Txs[0].ItemID < t.Txs[len(t.Txs)-1].ItemID {
-		t.Pagination.FirstReturnedItem = t.Txs[0].ItemID
-		t.Pagination.LastReturnedItem = t.Txs[len(t.Txs)-1].ItemID
-	} else {
-		t.Pagination.LastReturnedItem = t.Txs[0].ItemID
-		t.Pagination.FirstReturnedItem = t.Txs[len(t.Txs)-1].ItemID
-	}
-	return t.Pagination
+func (t testTxsResponse) GetPending() (pendingItems, lastItemID uint64) {
+	pendingItems = t.PendingItems
+	lastItemID = t.Txs[len(t.Txs)-1].ItemID
+	return pendingItems, lastItemID
 }
 
 func (t testTxsResponse) Len() int {

db/historydb/historydb.go

@@ -181,12 +181,11 @@ func (hdb *HistoryDB) GetBatchesAPI(
 	minBatchNum, maxBatchNum, slotNum *uint,
 	forgerAddr *ethCommon.Address,
 	fromItem, limit *uint, order string,
-) ([]BatchAPI, *db.Pagination, error) {
+) ([]BatchAPI, uint64, error) {
 	var query string
 	var args []interface{}
 	queryStr := `SELECT batch.*, block.timestamp, block.hash,
-	count(*) OVER() AS total_items, MIN(batch.item_id) OVER() AS first_item,
-	MAX(batch.item_id) OVER() AS last_item 
+	count(*) OVER() AS total_items
 	FROM batch INNER JOIN block ON batch.eth_block_num = block.eth_block_num `
 	// Apply filters
 	nextIsAnd := false
@@ -259,17 +258,13 @@ func (hdb *HistoryDB) GetBatchesAPI(
 	// log.Debug(query)
 	batchPtrs := []*BatchAPI{}
 	if err := meddler.QueryAll(hdb.db, &batchPtrs, query, args...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	batches := db.SlicePtrsToSlice(batchPtrs).([]BatchAPI)
 	if len(batches) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
-	return batches, &db.Pagination{
-		TotalItems: batches[0].TotalItems,
-		FirstItem:  batches[0].FirstItem,
-		LastItem:   batches[0].LastItem,
-	}, nil
+	return batches, batches[0].TotalItems - uint64(len(batches)), nil
 }
 
 // GetAllBatches retrieve all batches from the DB
@@ -367,12 +362,15 @@ func (hdb *HistoryDB) GetBestBidAPI(slotNum *int64) (BidAPI, error) {
 }
 
 // GetBestBidsAPI returns the best bid in specific slot by slotNum
-func (hdb *HistoryDB) GetBestBidsAPI(minSlotNum, maxSlotNum *int64, bidderAddr *ethCommon.Address, limit *uint, order string) ([]BidAPI, *db.Pagination, error) {
+func (hdb *HistoryDB) GetBestBidsAPI(
+	minSlotNum, maxSlotNum *int64,
+	bidderAddr *ethCommon.Address,
+	limit *uint, order string,
+) ([]BidAPI, uint64, error) {
 	var query string
 	var args []interface{}
 	queryStr := `SELECT b.*, block.timestamp, coordinator.forger_addr, coordinator.url, 
-	COUNT(*) OVER() AS total_items, MIN(b.slot_num) OVER() AS first_item, 
-	MAX(b.slot_num) OVER() AS last_item FROM (
+	COUNT(*) OVER() AS total_items FROM (
 	   SELECT slot_num, MAX(item_id) as maxitem 
 	   FROM bid GROUP BY slot_num
 	   )
@@ -399,28 +397,26 @@ func (hdb *HistoryDB) GetBestBidsAPI(minSlotNum, maxSlotNum *int64, bidderAddr *
 	query = hdb.db.Rebind(queryStr)
 	bidPtrs := []*BidAPI{}
 	if err := meddler.QueryAll(hdb.db, &bidPtrs, query, args...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	// log.Debug(query)
 	bids := db.SlicePtrsToSlice(bidPtrs).([]BidAPI)
 	if len(bids) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
-	return bids, &db.Pagination{
-		TotalItems: bids[0].TotalItems,
-		FirstItem:  bids[0].FirstItem,
-		LastItem:   bids[0].LastItem,
-	}, nil
+	return bids, bids[0].TotalItems - uint64(len(bids)), nil
 }
 
 // GetBidsAPI return the bids applying the given filters
-func (hdb *HistoryDB) GetBidsAPI(slotNum *int64, forgerAddr *ethCommon.Address, fromItem, limit *uint, order string) ([]BidAPI, *db.Pagination, error) {
+func (hdb *HistoryDB) GetBidsAPI(
+	slotNum *int64, forgerAddr *ethCommon.Address,
+	fromItem, limit *uint, order string,
+) ([]BidAPI, uint64, error) {
 	var query string
 	var args []interface{}
 	queryStr := `SELECT bid.*, block.timestamp, coordinator.forger_addr, coordinator.url, 
-	COUNT(*) OVER() AS total_items, MIN(bid.item_id) OVER() AS first_item, 
-	MAX(bid.item_id) OVER() AS last_item FROM bid
-	INNER JOIN block ON bid.eth_block_num = block.eth_block_num 
+	COUNT(*) OVER() AS total_items
+	FROM bid INNER JOIN block ON bid.eth_block_num = block.eth_block_num 
 	INNER JOIN coordinator ON bid.bidder_addr = coordinator.bidder_addr `
 	// Apply filters
 	nextIsAnd := false
@@ -469,21 +465,17 @@ func (hdb *HistoryDB) GetBidsAPI(slotNum *int64, forgerAddr *ethCommon.Address,
 	queryStr += fmt.Sprintf("LIMIT %d;", *limit)
 	query, argsQ, err := sqlx.In(queryStr, args...)
 	if err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	query = hdb.db.Rebind(query)
 	bids := []*BidAPI{}
 	if err := meddler.QueryAll(hdb.db, &bids, query, argsQ...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	if len(bids) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
-	return db.SlicePtrsToSlice(bids).([]BidAPI), &db.Pagination{
-		TotalItems: bids[0].TotalItems,
-		FirstItem:  bids[0].FirstItem,
-		LastItem:   bids[0].LastItem,
-	}, nil
+	return db.SlicePtrsToSlice(bids).([]BidAPI), bids[0].TotalItems - uint64(len(bids)), nil
 }
 
 // AddCoordinators insert Coordinators into the DB
@@ -562,10 +554,13 @@ func (hdb *HistoryDB) GetAllTokens() ([]TokenWithUSD, error) {
 }
 
 // GetTokens returns a list of tokens from the DB
-func (hdb *HistoryDB) GetTokens(ids []common.TokenID, symbols []string, name string, fromItem, limit *uint, order string) ([]TokenWithUSD, *db.Pagination, error) {
+func (hdb *HistoryDB) GetTokens(
+	ids []common.TokenID, symbols []string, name string, fromItem,
+	limit *uint, order string,
+) ([]TokenWithUSD, uint64, error) {
 	var query string
 	var args []interface{}
-	queryStr := `SELECT * , COUNT(*) OVER() AS total_items, MIN(token.item_id) OVER() AS first_item, MAX(token.item_id) OVER() AS last_item FROM token `
+	queryStr := `SELECT * , COUNT(*) OVER() AS total_items FROM token `
 	// Apply filters
 	nextIsAnd := false
 	if len(ids) > 0 {
@@ -616,21 +611,17 @@ func (hdb *HistoryDB) GetTokens(ids []common.TokenID, symbols []string, name str
 	queryStr += fmt.Sprintf("LIMIT %d;", *limit)
 	query, argsQ, err := sqlx.In(queryStr, args...)
 	if err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	query = hdb.db.Rebind(query)
 	tokens := []*TokenWithUSD{}
 	if err := meddler.QueryAll(hdb.db, &tokens, query, argsQ...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	if len(tokens) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
-	return db.SlicePtrsToSlice(tokens).([]TokenWithUSD), &db.Pagination{
-		TotalItems: tokens[0].TotalItems,
-		FirstItem:  tokens[0].FirstItem,
-		LastItem:   tokens[0].LastItem,
-	}, nil
+	return db.SlicePtrsToSlice(tokens).([]TokenWithUSD), uint64(len(tokens)) - tokens[0].TotalItems, nil
 }
 
 // GetTokenSymbols returns all the token symbols from the DB
@@ -813,9 +804,9 @@ func (hdb *HistoryDB) GetHistoryTxs(
 	ethAddr *ethCommon.Address, bjj *babyjub.PublicKey,
 	tokenID *common.TokenID, idx *common.Idx, batchNum *uint, txType *common.TxType,
 	fromItem, limit *uint, order string,
-) ([]TxAPI, *db.Pagination, error) {
+) ([]TxAPI, uint64, error) {
 	if ethAddr != nil && bjj != nil {
-		return nil, nil, errors.New("ethAddr and bjj are incompatible")
+		return nil, 0, errors.New("ethAddr and bjj are incompatible")
 	}
 	var query string
 	var args []interface{}
@@ -827,8 +818,7 @@ func (hdb *HistoryDB) GetHistoryTxs(
 	tx.load_amount, tx.load_amount_usd, tx.fee, tx.fee_usd, tx.nonce,
 	token.token_id, token.item_id AS token_item_id, token.eth_block_num AS token_block,
 	token.eth_addr, token.name, token.symbol, token.decimals, token.usd,
-	token.usd_update, block.timestamp, count(*) OVER() AS total_items, 
-	MIN(tx.item_id)  OVER() AS first_item, MAX(tx.item_id) OVER() AS last_item 
+	token.usd_update, block.timestamp, count(*) OVER() AS total_items 
 	FROM tx INNER JOIN token ON tx.token_id = token.token_id 
 	INNER JOIN block ON tx.eth_block_num = block.eth_block_num `
 	// Apply filters
@@ -924,17 +914,13 @@ func (hdb *HistoryDB) GetHistoryTxs(
 	// log.Debug(query)
 	txsPtrs := []*TxAPI{}
 	if err := meddler.QueryAll(hdb.db, &txsPtrs, query, args...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	txs := db.SlicePtrsToSlice(txsPtrs).([]TxAPI)
 	if len(txs) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
-	return txs, &db.Pagination{
-		TotalItems: txs[0].TotalItems,
-		FirstItem:  txs[0].FirstItem,
-		LastItem:   txs[0].LastItem,
-	}, nil
+	return txs, txs[0].TotalItems - uint64(len(txs)), nil
 }
 
 // GetAllExits returns all exit from the DB
@@ -972,9 +958,9 @@ func (hdb *HistoryDB) GetExitsAPI(
 	ethAddr *ethCommon.Address, bjj *babyjub.PublicKey, tokenID *common.TokenID,
 	idx *common.Idx, batchNum *uint, onlyPendingWithdraws *bool,
 	fromItem, limit *uint, order string,
-) ([]ExitAPI, *db.Pagination, error) {
+) ([]ExitAPI, uint64, error) {
 	if ethAddr != nil && bjj != nil {
-		return nil, nil, errors.New("ethAddr and bjj are incompatible")
+		return nil, 0, errors.New("ethAddr and bjj are incompatible")
 	}
 	var query string
 	var args []interface{}
@@ -984,8 +970,7 @@ func (hdb *HistoryDB) GetExitsAPI(
 	exit_tree.delayed_withdraw_request, exit_tree.delayed_withdrawn,
 	token.token_id, token.item_id AS token_item_id,
 	token.eth_block_num AS token_block, token.eth_addr, token.name, token.symbol,
-	token.decimals, token.usd, token.usd_update, COUNT(*) OVER() AS total_items,
-	MIN(exit_tree.item_id) OVER() AS first_item, MAX(exit_tree.item_id) OVER() AS last_item
+	token.decimals, token.usd, token.usd_update, COUNT(*) OVER() AS total_items
 	FROM exit_tree INNER JOIN account ON exit_tree.account_idx = account.idx 
 	INNER JOIN token ON account.token_id = token.token_id `
 	// Apply filters
@@ -1071,16 +1056,12 @@ func (hdb *HistoryDB) GetExitsAPI(
 	// log.Debug(query)
 	exits := []*ExitAPI{}
 	if err := meddler.QueryAll(hdb.db, &exits, query, args...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	if len(exits) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
-	return db.SlicePtrsToSlice(exits).([]ExitAPI), &db.Pagination{
-		TotalItems: exits[0].TotalItems,
-		FirstItem:  exits[0].FirstItem,
-		LastItem:   exits[0].LastItem,
-	}, nil
+	return db.SlicePtrsToSlice(exits).([]ExitAPI), exits[0].TotalItems - uint64(len(exits)), nil
 }
 
 // // GetTx returns a tx from the DB
@@ -1337,11 +1318,11 @@ func (hdb *HistoryDB) GetCoordinatorAPI(bidderAddr ethCommon.Address) (*Coordina
 }
 
 // GetCoordinatorsAPI returns a list of coordinators from the DB and pagination info
-func (hdb *HistoryDB) GetCoordinatorsAPI(fromItem, limit *uint, order string) ([]CoordinatorAPI, *db.Pagination, error) {
+func (hdb *HistoryDB) GetCoordinatorsAPI(fromItem, limit *uint, order string) ([]CoordinatorAPI, uint64, error) {
 	var query string
 	var args []interface{}
 	queryStr := `SELECT coordinator.*, 
-	COUNT(*) OVER() AS total_items, MIN(coordinator.item_id) OVER() AS first_item, MAX(coordinator.item_id) OVER() AS last_item
+	COUNT(*) OVER() AS total_items
 	FROM coordinator `
 	// Apply filters
 	if fromItem != nil {
@@ -1365,16 +1346,13 @@ func (hdb *HistoryDB) GetCoordinatorsAPI(fromItem, limit *uint, order string) ([
 
 	coordinators := []*CoordinatorAPI{}
 	if err := meddler.QueryAll(hdb.db, &coordinators, query, args...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	if len(coordinators) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
-	return db.SlicePtrsToSlice(coordinators).([]CoordinatorAPI), &db.Pagination{
-		TotalItems: coordinators[0].TotalItems,
-		FirstItem:  coordinators[0].FirstItem,
-		LastItem:   coordinators[0].LastItem,
-	}, nil
+	return db.SlicePtrsToSlice(coordinators).([]CoordinatorAPI),
+		coordinators[0].TotalItems - uint64(len(coordinators)), nil
 }
 
 // AddAuctionVars insert auction vars into the DB
@@ -1394,7 +1372,8 @@ func (hdb *HistoryDB) GetAuctionVars() (*common.AuctionVariables, error) {
 // GetAccountAPI returns an account by its index
 func (hdb *HistoryDB) GetAccountAPI(idx common.Idx) (*AccountAPI, error) {
 	account := &AccountAPI{}
-	err := meddler.QueryRow(hdb.db, account, `SELECT account.item_id, hez_idx(account.idx, token.symbol) as idx, account.batch_num, account.bjj, account.eth_addr,
+	err := meddler.QueryRow(hdb.db, account, `SELECT account.item_id, hez_idx(account.idx, 
+	token.symbol) as idx, account.batch_num, account.bjj, account.eth_addr,
 	token.token_id, token.item_id AS token_item_id, token.eth_block_num AS token_block,
 	token.eth_addr as token_eth_addr, token.name, token.symbol, token.decimals, token.usd, token.usd_update 
 	FROM account INNER JOIN token ON account.token_id = token.token_id WHERE idx = $1;`, idx)
@@ -1407,16 +1386,19 @@ func (hdb *HistoryDB) GetAccountAPI(idx common.Idx) (*AccountAPI, error) {
 }
 
 // GetAccountsAPI returns a list of accounts from the DB and pagination info
-func (hdb *HistoryDB) GetAccountsAPI(tokenIDs []common.TokenID, ethAddr *ethCommon.Address, bjj *babyjub.PublicKey, fromItem, limit *uint, order string) ([]AccountAPI, *db.Pagination, error) {
+func (hdb *HistoryDB) GetAccountsAPI(
+	tokenIDs []common.TokenID, ethAddr *ethCommon.Address,
+	bjj *babyjub.PublicKey, fromItem, limit *uint, order string,
+) ([]AccountAPI, uint64, error) {
 	if ethAddr != nil && bjj != nil {
-		return nil, nil, errors.New("ethAddr and bjj are incompatible")
+		return nil, 0, errors.New("ethAddr and bjj are incompatible")
 	}
 	var query string
 	var args []interface{}
-	queryStr := `SELECT account.item_id, hez_idx(account.idx, token.symbol) as idx, account.batch_num, account.bjj, account.eth_addr,
-	token.token_id, token.item_id AS token_item_id, token.eth_block_num AS token_block,
+	queryStr := `SELECT account.item_id, hez_idx(account.idx, token.symbol) as idx, account.batch_num, 
+	account.bjj, account.eth_addr, token.token_id, token.item_id AS token_item_id, token.eth_block_num AS token_block,
 	token.eth_addr as token_eth_addr, token.name, token.symbol, token.decimals, token.usd, token.usd_update, 
-	COUNT(*) OVER() AS total_items, MIN(account.item_id) OVER() AS first_item, MAX(account.item_id) OVER() AS last_item  
+	COUNT(*) OVER() AS total_items
 	FROM account INNER JOIN token ON account.token_id = token.token_id `
 	// Apply filters
 	nextIsAnd := false
@@ -1464,21 +1446,18 @@ func (hdb *HistoryDB) GetAccountsAPI(tokenIDs []common.TokenID, ethAddr *ethComm
 	queryStr += fmt.Sprintf("LIMIT %d;", *limit)
 	query, argsQ, err := sqlx.In(queryStr, args...)
 	if err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	query = hdb.db.Rebind(query)
 
 	accounts := []*AccountAPI{}
 	if err := meddler.QueryAll(hdb.db, &accounts, query, argsQ...); err != nil {
-		return nil, nil, err
+		return nil, 0, err
 	}
 	if len(accounts) == 0 {
-		return nil, nil, sql.ErrNoRows
+		return nil, 0, sql.ErrNoRows
 	}
 
-	return db.SlicePtrsToSlice(accounts).([]AccountAPI), &db.Pagination{
-		TotalItems: accounts[0].TotalItems,
-		FirstItem:  accounts[0].FirstItem,
-		LastItem:   accounts[0].LastItem,
-	}, nil
+	return db.SlicePtrsToSlice(accounts).([]AccountAPI),
+		accounts[0].TotalItems - uint64(len(accounts)), nil
 }

db/utils.go

@@ -179,21 +179,6 @@ func SlicePtrsToSlice(slice interface{}) interface{} {
 	return res.Interface()
 }
 
-// Pagination give information on the items of a query
-type Pagination struct {
-	TotalItems        uint64 `json:"totalItems"`
-	FirstItem         uint64 `json:"firstItem"`
-	LastItem          uint64 `json:"lastItem"`
-	FirstReturnedItem uint64 `json:"-"`
-	LastReturnedItem  uint64 `json:"-"`
-}
-
-// Paginationer is an interface that allows getting pagination info on any struct
-type Paginationer interface {
-	GetPagination() *Pagination
-	Len() int
-}
-
 // Rollback an sql transaction, and log the error if it's not nil
 func Rollback(txn *sql.Tx) {
 	err := txn.Rollback()