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<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2020-11-11T21:58:31.0241152+00:00 -->
<!-- Version            : 5.0.1.513 -->
<!-- Package ID         : d5e4058c97344f4b828109fca44531f1 -->
<!-- Copyright (c) 2020 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="ddog_DebtInstrumentConvertibleThresholdMaximumPercentageOfProductOfLastReportedSalePriceOfCommonStock" name="DebtInstrumentConvertibleThresholdMaximumPercentageOfProductOfLastReportedSalePriceOfCommonStock" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_DebtInstrumentPrincipalAmountDenominationForConversionIntoCommonStock" name="DebtInstrumentPrincipalAmountDenominationForConversionIntoCommonStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="ddog_DebtInstrumentDiscountForConversionOption" name="DebtInstrumentDiscountForConversionOption" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="ddog_DebtIssuanceCostAttributableToLiabilityComponent" name="DebtIssuanceCostAttributableToLiabilityComponent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="ddog_DebtIssuanceCostAttributableToEquityComponent" name="DebtIssuanceCostAttributableToEquityComponent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="ddog_InitialCapPricePerShareOfCappedCalls" name="InitialCapPricePerShareOfCappedCalls" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_CommonStockCoveredUnderCappedCallsTransaction" name="CommonStockCoveredUnderCappedCallsTransaction" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_CostIncurredToPurchaseCappedCalls" name="CostIncurredToPurchaseCappedCalls" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="ddog_ContingentFederalPayrollTaxLiability" name="ContingentFederalPayrollTaxLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="ddog_LesseeOperatingLeaseExpirationPeriod" name="LesseeOperatingLeaseExpirationPeriod" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_LesseeOperatingLeaseTerminationTerm" name="LesseeOperatingLeaseTerminationTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_LesseeOperatingLeaseNotYetCommencedOneMember" name="LesseeOperatingLeaseNotYetCommencedOneMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_LesseeOperatingLeaseNotYetCommencedTwoMember" name="LesseeOperatingLeaseNotYetCommencedTwoMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_OperatingLeaseNonCashLeaseExpense" name="OperatingLeaseNonCashLeaseExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="ddog_LesseeOperatingLeaseCommencingPeriod" name="LesseeOperatingLeaseCommencingPeriod" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_LesseeOperatingLeaseCommencingPeriodMonthAndYear" name="LesseeOperatingLeaseCommencingPeriodMonthAndYear" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_InternationalMember" name="InternationalMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_IncreaseDecreaseInDeferredContractCosts" name="IncreaseDecreaseInDeferredContractCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="ddog_TwoThousandNineteenEquityIncentivePlanMember" name="TwoThousandNineteenEquityIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_EmployeeStockPurchasePlanMember" name="EmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_CommonStockIssuedSubjectToRepurchaseRelatedToEarlyExerciseOfOptions" name="CommonStockIssuedSubjectToRepurchaseRelatedToEarlyExerciseOfOptions" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="ddog_EmployeeStockPurchasePlansPurchasePricePerSharePercentage" name="EmployeeStockPurchasePlansPurchasePricePerSharePercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_OtherNonoperatingIncomeExpenseNet" name="OtherNonoperatingIncomeExpenseNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="ddog_IncomeTaxesLineItems" name="IncomeTaxesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_IncomeTaxesTable" name="IncomeTaxesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_PropertyRecoveryCorrectionPeriod" name="PropertyRecoveryCorrectionPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_NetOperatingLossDeductibleLimitationPercentage" name="NetOperatingLossDeductibleLimitationPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_NetOperatingLossesCarrybackPeriod" name="NetOperatingLossesCarrybackPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_ReallocationOfUndistributedIncomeLossResultOfConversionOfCommonStock" name="ReallocationOfUndistributedIncomeLossResultOfConversionOfCommonStock" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="ddog_WeightedAverageNumberDilutedSharesOutstandingConversionOfCommonSharesClass" name="WeightedAverageNumberDilutedSharesOutstandingConversionOfCommonSharesClass" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="ddog_EmployeeStockOptionAndRestrictedStockUnitMember" name="EmployeeStockOptionAndRestrictedStockUnitMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="ddog_UnvestedEarlyExercisedStockOptionsAndRestrictedStockMember" name="UnvestedEarlyExercisedStockOptionsAndRestrictedStockMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
